LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


OK 


Mrs.  SARAH  P.  WALSWORTH. 

Received  October,  1894. 
Accessions  No. Class  Mo. 


ELEMENTS 


CHEMISTRY; 


CONTAINING   THE 


PRINCIPLES  OF  THE  SCIENCE, 

*.  -'    *  »  *>. 


EXPERIMENTAL  AND  PRACTICAL, 


INTENDED  AS  A  TEXT-BOOK  FOR  ACADEMIES,  HIGH   SCHOOLS, 
AND  COLLEGES. 


ILLUSTRATED  WITH  NUMEROUS  ENGRAVINGS. 

BY  ALONZO  GRAY,  A.  M. 

Teacher  of  Chemistry  and  Nat.  Hist,  in  the  Teachers  Sem.,  Andover,  Mass. 
SECOND  EDITION,  REVISED  AND  ENLARGED. 


NEW    YORK: 
PUBLISHED    BY    DAYTON    AND    S  A  X  T  O  N, 

SCHOOL  BOOK  PUBLISHERS, 

Corner  of  Fulton  and  Nassau  Streets. 

BOSTON  :    SAXTON  AND  PIERCE. 

1841. 

fll? 


Entered  according  to  Act  of  Congress,  in  the  year  13-iO, 

Bv  AI.ON/.O  GRAY, 
In  the  Clerk's  Office  of  the  District  Court  of  Massachusetts. 


\ 

ALLEN,    MORRELL,  AND    WARDWELL, 
PRINTERS. 


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>» 


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PREFACE. 


IN  compiling  tlie  first  edition  of  this  work,  the  author 
attempted  to  prepare  a  text-book  which  should  be  well 
fitted  for  elementary  instruction.  Most  of  the  works  on 
chemistry  appeared  to  him  to  be  either  too  profound,  on  the 
one  hand,  for  those  who  were  just  commencing  the  study,  or 
too  superficial,  on  the  other,  for  those  who  wished  to  obtain 
a  scientific  knowledge  of  the  subject. 

The  design  was  to  avoid  these  two  extremes,  and  com- 
bine the  scientific  with  the  popular  and  useful  parts  of  the 
subject.  The  rapid  sale  of  the  first  edition,  and  its  intro- 
duction into  'several  colleges,  has  led  to  the  inference  that 
the  attempt  has  not  been  wholly  unsuccessful.  The  author 
has  therefore  been  induced  to  revise  and  enlarge  the  work, 
and  put  it  into  a  permanent  form.  A  large  amount  of 
matter,  and  numerous  engravings,  have  been  added,  for  the 
purpose  of  rendering  the  work  better  adapted  to  academies 
and  other  schools. 

It  is  believed  that  greater  success  would  attend  the  efforts 
of  teachers  in  this  branch  of  science,  if  more  attention  were 
given  to  the  principles  of  chemistry,  and  less  to  its  details. 
The  fundamental  principles  being  thoroughly  understood  by 
the  *  student,  he  is  prepared  to  attend  to  the  details  with 
greater  pleasure  and  success,  as  he  will  be  able  to  connect 
the  effects  with  their  appropriate  causes. 

Under  the  influence  of  this  belief,  the  author  has  given  a 
greater  prominence  to  the  imponderable  agents  and  the  thir- 


PREFACE. 


teen  non-metallic  substances,  than  to  other  parts  of  the  work. 
Most  of  the  illustrations  and  experiments  are  introduced  in 
this  part,  so  as  to  present  and  illustrate  the  philosophy  of 
chemical  combinations,  and  the  general  nature  of  the  com- 
pounds thus  formed  ;  in  other  words,  the  causes  of  chemical 
changes  and  the  mode  of  studying  them. 

By  the  introduction  of  numerous  experiments  and  illus- 
trations, the  object  has  been  to  give  to  the  work  a  prac- 
tical character,  so  that  the  teacher,  with  a  very  simple 
apparatus,  and  with  limited  means,  may  be  able  to  give 
numerous  experimental  illustrations  to  his  classes.  The  im- 
portance of  studying  chemistry  experimentally,  is  admitted 
by  all ;  and  to  aid  teachers  in  constructing  the  more  simple 
forms  of  apparatus,  many  notes  and  drawings  have  been 
added,  and  experiments  described,  which  may  easily  be 
performed  by  those  who  are  not  privileged  with  more  costly 
and  extensive  means  of  illustration. 

In  the  arrangement  of  the  imponderable  agents,  the  phe- 
nomena of  common  and  voltaic  electricity,  electro-magnet- 
ism, and  magneto-electricity,  are  classed  as  effects  of  one- 
agent  —  electricity. 

In  the  arrangement  of  the  simple  substances,  the  logical 
order  has  been  adopted ;  that  is,  each  simple  substance  is 
described,  and  then  its  combinations  with  those  only  which 
have  been  previously  described  ;  so  that  only  one  substance 
with  which  the  pupil  is  unacquainted  is  presented  at  a  time. 
This  classification  appears  to  be  the  most  convenient  for 
presenting  the  different  compounds,  and  less  liable  than  any 
other  to  confuse  the  mind  of  the  learner.  "This  order,  how- 
ever, has  been  adopted  only  with  the  simple  substances  and 
their  binary  compounds. 

The  salts  occupy  a  separate  chapter,  in  the  arrangement 
of  which  Turner's  Chemistry  has  been  made  the  basis. 
Several  new  salts,  and  one  entire  family,  —  the  silicates,  — 
have  been  added. 


PREFACE.  P 

Organic  chemistry  has  become  so  extensive,  and  so  far  a 
distinct  branch  of  the  subject,  that  a  short  chapter  only  is 
inserted.  For  a  complete  description  of  these  compounds, 
the  student  is  referred  to  Thompson's  Chemistry,  "  Organic 
Bodies,"  which  is  the  most  extensive  and  valuable  work  on 
the  subject  which  has  hitherto  appeared. 

The  chapter  on  Analytical  Chemistry  has  been  consider- 
ably enlarged  ;  but  the  methods  of  analysis  have  become  so 
accurate,  the  details  so  minute,  and  the  processes  so  com- 
plicated, that  those  who  would  obtain  a  full  mastery  of  the 
subject,  must  consult  works  which  treat  particularly  of 
:ical  analysis.  Sufficient  only  has  been  inserted  to 
give  the  pupil  some  idea  of  the  nature  of  the  processes,  and 
to  enable  him  to  test,  if  not  actually  to  analyze,  the  sub- 
stances which  are-mentioned. 

The  Glossary  of  chemical  terms  has  been  selected  from 
that  prepared  by  Daniell,  of  London,  and  adapted  to  this 
work.  The  table  of  contents  has  been  much  enlarged,  and 
a  complete  analysis  of  the  work  presented,  in  the  form  of 
topics,  which  are  intended  to  be  used  instead  of  questions ; 
the  topics  being  so  arranged  that,  when  the  teacher  sug- 
gests one,  the  pupil  may  give  a  complete  description  of  it. 
This  plan,  it  is  believed,  will  prevent  the  evils  incident  to 
direct  questions,  while  it  will  secure  all  their  advantages. 

Chemical  formulae  have  been  extensively  adopted.  This 
appears  highly  important,  especially  for  those  who  intend 
to  become  thorough  students  in  the  science.  The  notation, 
(the  use  of  symbolical  language,)  to  express,  in  a  condensed 
form,  complicated  chemical  changes,  seems  to  be  as  useful 
in  chemistry  as  in  a]gebra,  and,  although  these  symbols  may 
be  unintelligible  to  the  common  reader,  he  who  will  thorough- 
ly study  them  will  find  them  the  most  efficient  aid  to  a  clear, 
definite,  and  easy  comprehension  of  the  whole  science. 

In  the  description  of  the  ponderable  bodies,  brevity  has 


PREFACE. 

been  consulted,  as  far  as  was  consistent  with  perspicuity. 
The  illustrations  and  descriptions  are  much  more  extended 
in  the  first  two  hundred  pages  than  in  other  parts  of  the 
work.  The  method  of  description  which  is  employed  in 
natural  history  has  been  adopted,  where  the  subject  did 
not  require  a  more  popular  style.  By  this  means,  and  by 
using  different  kinds  of  type,  a  large  amount  of  matter  has 
been  condensed  into  a  small  compass,  while,  at  the  same 
time,  that  which  is  more  important  to  be  studied  is  rendered 
conspicuous.  Many  subjects  of  minor  importance  are  only 
alluded  to,  and  reference  frequently  made  to  more  extensive 
works. 

The  source  from  which  most  of  the  materials  have  been 
drawn,  is  Turner's  Chemistry.  The  works  of  Henry,  Silli- 
man,  Webster,  and  Griffin's  Chemical  Recreations,  have 
been  frequently  consulted,  and  also  many  original  papers  in 
the  scientific  journals  of  the  day  ;  and  it  is  confidently  be- 
lieved that  the  work  contains  the  most  valuable  recent 
discoveries  up  to  the  present  time,  so  far,  at  least,  as  they 
have  been  made  known  to  the  scientific  public. 

The  acknowledgments  of  the  author  are  here  due  to 
Professor  Charles  B.  Adams,  of  Middlebury  College,  for 
important  aid,  especially  in  the  department  of  Organic 
Chemistry. 

A.  G. 

TEACHERS'  SEMINARY, 

Andover,  September,  1841. 


CONTENTS. 


INTRODUCTION. 

Page 
Science  defined  —  Physical  and  Natural  science 21 

Definition  of  matter  —  how  many  properties  does  it  embrace  ? 21 

DIVISION  or  NATURAL  SCIENCE. 

I.  NATURAL  PHILOSOPHY — method  and  object  of. 21 

II.  CHEMISTRY  —  method  and  object  of. 22 

III.  NATURAL  HISTORY — method  and  object  of 22 

PLAN  OF  THE  WORK. 

PART  I.  IMPONDERABLE  AGENTS  —  why  so  called 22 

II.  CHEMICAL  AFFINITY— definition  of. 23 

III.  PONDERABLE  BODIES  —  chemical  and  natural  substances.  24 
Division  of  substances  ;  simple  and  compound  bodies. ...  24 
Analysis  and  synthesis;  arrangement  of  chem.  substances  24 

PART   FIRST. 

IMPONDERABLE    AGENTS. 

CHAPTER  I.  — CALORIC. 

The  term  heat  how  used  —  meaning  of  caloric 25 

1.  Sensible  caloric  defined. — 2.  Insensible  caloric  do 25 

SECT.  1.     SENSIBLE  CALORIC — COMMUNICATION  OF. 

The  most  important  property  of  sensible  caloric 26 

I.  Conduction  —  meaning  and  illustration  of. 26 

Conducting  power  ;  how  does  it  differ  in  bodies  ? 26 

Different  degrees  of  this  power  illustrated 27 

1.  Conducting  power  of  solids  ;  illustrated  by  conductometer 27 

Best  and  poorest  conductors,  metals,  stones 27 

Uses  of  conductors,  benevolence  of  God  illustrated 28 

Ratio  of  the  conducting  power  of  solids 28 

2.  Conducting  power  of  liquids  ;  how  are  liquids  heated  ?  Ills 28 

Heat  applied  at  the  top  of  liquids  in  a  glass  jar 29 

3.  Conducting  power  of  gases ;  how  are  they  heated  ? 29 

II.  Radiation — defined;  radiant  caloric,  how  projected  ? 30 

3 .   Law  of  the  intensity  of  heat  at  different  distances 30 

2.   Degree  of  radiation,  dependent  upon  what  ? 30 

Difference  between  bright,  and  dark  or  rough  surfaces,  Ills 30 

Greater  radiating  power  of  rough  surfaces,  depends  on  what?. .  30 


8  CONTENTS. 

3.  Rapidity  of  radiation  dependent  upon  .what  ? 31 

III.  Disposition  of  Radiant  Caloric  —  reflect.,  absorb.,  transmit.  31 

1.  Reflection  of  caloric  ;  law  of  reflection,  angles  of  incidence  and 

reflection.     Concave  mirrors  described 31 

2.  Absorption  of  caloric ;  depends  upon  what  ? 32 

Best  absorbers,  reflectors,  and  radiators 32 

Color  of  surface  ;  its  effect  upon  the  power  of  absorp.,  Ills 32 

3.  Transmission  of  caloric ;  through  air  and  gases,  glass,  etc 32 

Opinions  of  Leslie,  Brewster,  De  la  Roche,  and  other  chemists.  33 

Radiant  caloric  modified  by  its  connection  with  solar  light 33 

IV.  Theories  of  Radiation  —  how  many  are  worthy  of  notice  ?. .  33 

1.  Theory  of  Pictet,  described 33 

2.  Theory  of  Prevost,     do.      grounds  of  preference 33 

V.  Application  of  the  Theory  of  Prevost  to  the  Expl.  of -carts  Phen. 

1.  The  phen.  of  the  mirrors  explained  ;  apparent  radiation  of  cold..  34 

2.  Formation  of  dew,  process  described  and  explained 34 

Quantity  of  dew  ;  dep.  upon  what?  grass,  and  polished  surface..  34 
Why  is  there  no  dew  in  a  cloudy  night  ? 35 

VI.  Cooling  of  Bodies  —  different  modes  by  which  it  is  effected.  35 
Velocity  of  cooling,  defined;  law  of  cooling,  according  to  Newton.  35 

VII.  Prac.  Application  of  the  Laws  of  Conduct,  and  Radiant  Caloric. 

Best  materials  for  windows ;  double  walls,  doors,  windows 35 

Object  of  clothing  ;  kind  best  for  different  season*  of  the  year 36 

Effects  of  Free  Caloric. 

I.  General  Law  — Caloric  expands  all  Bodies;  Liquids,  Solids,  Gases. 

1.  Caloric  expands  solids  :  illustrated  by  what  ? 36 

2.  Equal  degrees  of  caloric  expand  some  solids  more  than  others. . .  36 
Illustrated  by  pyrometer ;  description  of  pyrometer 36 

3.  Effect  of  equal  add'ns  of  caloric  on  the  same  solid  at  dif.  temp's.  37 
Expansion  of  brass  and  iron  rods  in  the  higher  or  lower  temp  s. .  37 

4.  Uniformity  in  the  expansion  of  certain  solids 37 

II.  Caloric  expands  Liquids  more  than  Solids. 

1.  Illustrated  by  heating  water  in  a  glass  tube,  common  thermom'r  38 

2.  Effect  upon  different  liquids  of  equal  degrees  of  caloric 38 

3.  Effect  upon  the  same  liquids  of  equal  degrees  at  different  temp's  38 
Apparent  exceptions  to  the  general  law  that  heat  expands 38 

III.  Caloric  expands  Gases  more  than  Solids  or  Liquids. 

1.  The  expansion  of  air  ;  in  glass  ball,  bladder 38 

2.  Law  of  the  expansion  of  gases  at  all  temperatures 39 

Difference  between  gases,  and  solids  or  liquids 39 

Theory  of  expansion  ;  caloric  and  cohesion,  how  related  ? 39 

IV.  Apparent  Exceptions  to  the  General  Law. 

Water  near  the  point  of  congelation ;  Illustration 40 

V.  Force  of  Expansion  when  Water  freezes. 

Florentine  Academicians  ;  experiments  of  Major  Williams 40 

Theory,  or  the  cause  of  expansion  when  water  freezes 40 

VI.  Advantages  of  this  Excep.  —  wisdom  and  benevolen.  of  God  40 
Process  of  freezing  water ;  effect  if  the  contractions  continued. ...  41 
Cast  iron  and  antjmony,  how  affected  in  cooling  ? 41 

VII.  Practical  Uses  of  the  General  Law  of  Expansion  and  Contract. 

Banding  of  wheels,  steam-engine  boilers,  gallery  at  Paris 41 

Winds  ;  depend  upon  what  ?  land  and  sea  breezes 42 

Thermometers  ;  by  whom  invented  ? 42 

1.  Air  thermometers  j  plan  of  Sanctorius,  illustrated 42 


CONTENTS.  9 

Objections  to  air  for  the  common  purposes  of  a  thermometer ....  43 

2.  Differential  thermometer  of  Leslie  ;  mode  of  construction 43 

Best  substance  for  thermometers ;  solids,  liquids,  or  gases  ? 43 

3.  Mercurial  thermometer;  construction  and  graduation 44 

Different  scales;  Fahrenheit's,  Reaumur's,  De  Lisle's,  Celsius's  45 

4.  Register  thermometer;  construction,  object,  and  principle  of...  45 
Pyrometers  ;  derivation  and  meaning  of  the  term 46 

1.  Pyrometer  of  Wedgwood ;  founded  upon  what  property 46 

2.  do.       of  Daniell ;  construction  of. 46 

3.  Metallic  thermometer  of  Brequet ;  construction,  Illustrated 46 

Amount  of  knowledge  obtained  by  therm's  and  other  instruments  47 

SECT.  2.     INSENSIBLE  CALORIC. 

Specific  caloric ;  meaning  of,  illustrated 47 

Methods  of  determining  specific  heat  of  solids  and  liquids 48 

Laws  of  Specific  Heat,  1,  2,  3,  4,  5 48 

Practical  inference  from  the  doctrine  of  specific  heat 49_ 

Effects  of  Insensible  Caloric. 

I.  Liquefaction  —  states  in  which  bodies  exist 49 

1 .  Point  of  liquefaction ;  fusion,  congelation 49 

2.  Caloric  of  fluidity  ;  Illustr.,  quantity  in  different  substances. ...  49 

3.  Freezing  mixtures;  how  produced?  salt  and  snow 50 

4.  Limit  to  the  degree  of  cold  ;  greatest  cold  by  these  processes. . .  51 

5.  Absolute  amount  of  heat ;  estimated  by  what  means  ? 52 

II.  Vaporization  —  defined,  difference  between  gas  and  vapor. ..  52 

Definition  of  volatile  and  fixed  bodies ;  liquids  how  vaporized 52 

Ebullition ;  \ .  Boiling  point  defined ;  is  it  fixed  ? 52 

2.  Circumstances  which  modify  the  boiling  point  of  liquids 53 

Pressure  of  the  atmosphere  ;  variations  of 53 

Barometer,  construction  and  illustration  of. 53 

1.  Law  of  the  boiling  point  as  the  pressure  diminishes 53 

Mercury  frozen  under  the  exhausted  receiver  of  an  air-pump . .  53 

2.  Law  of  the  boiling  point  as  the  pressure  increases 54 

Marcet's  digester ;   construction  of. •. 55 

Absorption  of  free  caloric  in  ebullition,  Illustration 55 

Table  of  the  latent  heat  of  different  vapors 56 

Steam  ;  its  formation  and  laws  of  expansive  force 56 

Sensible  and  insensible  caloric  of  steam  at  all  temperatures 57 

Application  of  Steam  to  practical  Purposes. 

1 .  Warming  rooms ;  water  baths,  dyeing  vats,  etc 57 

2.  Steam  engine ;  invention  of.  principle  illustrated 58 

3.  Steam  generator  of  Mr.  Perkins  ;  steam  artillery 58 

Distillation;  process  illustrated  and  described 59 

Evaporation  —  difference  between  it  and  ebullition 59 

1.  Evaporation  of  different  liquids  ;  depends  upon  what  ? 59 

2.  Effect  of  increased  and  diminished  pressure  upon  evaporation. . .  59 

3.  Extent  of  surface  ;  how  does  it  affect  the  rapidity  of  evaporation  60 

4.  State  of  the  atmosphere;         "                 "             "                 «  60 

5.  Absorption  of  free  Caloric  by  Evaporation ;  cryophorus  described  CO 

6.  Cause  of  evaporation  ;  how  have  some  accounted  for  it  ?....,...  61 

7.  Uses  of  evaporation ;  cooling  rooms,  warm  climates 61 

Effect  of  perspiration  explained ;  fire  kings,  oven  girls 61 

Injurious  effects  of  evaporation,  miasma,  fever  and  ague 62 


10  CONTENDS. 

Hygrometers ;  reduced  to  three  principle* 62 

1.  Saussure's  hygrometer ;  depends  up^n  what  property  ? 62 

2.  Leslie's  hygrometer ;  depends  upon  what  property  ? 62 

3.  Hygrometer  depending  upon  the  quantity  of  dew,  etc 62 

Application  of  the  Laws  of  Insensible  Caloric  to  the  Expl.  Nat.  Phen. 

1.  Processes  of  thawing  and  freezing ;  effect  upon  climate 62 

2.  Effect  of  vaporization ;  to  modify  the  heat  of  summer 63 

3.  Effect  of  condensing  vapors ;  rain,  source  of  the  cold 63 

•4.  Effect  of  freezing  water;  to  modify  the  approach  of  winter 63 

Why  are  the  shores  of  a  country  warmer  in  winter,  etc 63 

SECT.  3.     SOURCES  OF  CALORIC  AND  OF  COLD. 

1.  Sun  ;  concentration  of  its  rays,  degree  of  heat 64 

2.  Chemical  action ;  combustion  defined 64 

3.  Condensation  ;  machinery,  friction,  percussion 64 

4.  Vital  action  ;  how  is  caloric  produced  in  animals  ? 65 

Sources  of  cold,  what? 65 

SECT.  4.     NATURE  OF  CALORIC. 

Theory  of  Sir  W.  Herschel  and  Prof.  Airy ;  undulatory  theory 65 

Theory  of  Newton ;  what  supposition  did  he  make  ? 65 

CHAPTER  II.  — LIGHT. 

I.  Physical  Properties  of  Light  —  belong  to  what  science  ? 66 

Velocity  of  light ;  disposition  of  it 66 

II.  Reflection —  the  circumstances  which  govern  it 66 

III .  Refraction  —  defined,  refrangibility,  Illustration 66 

IV.  Decomposition  of  Light —  how  many  kinds  of  rays  ? 67 

1.  Colorific  rays;  mode  of  separating  them  by  prism,  Illustration..  67 
Opinion  of  Wollaston,  of  Brewster,  illuminating  power 68 

2.  Calorific  rays ;  their  position,  and  degree  of  refrangibility 68 

3.  Chemical  rays  ;  their  position  in  the  spectrum <!rt 

1.  Photographic  drawing,  Ills.     2.  Daguerreotype  described ...  68 

Magnetic  rays  ;  do  they  exist  ? 69 

V.  Absorption  —  defined 69 

1.  Effect  of  different  surfaces  to  absorb  different  colors 69 

Why  are  objects  colored?  what  produces  the  variety  ? 69 

2.  Effect  of  chemical  constitution  upon  the  power  of  absorption ...  69 

3.  Effect  of  absorbing  all  the  rays .  .x 69 

VI.  Ignition  and  Incandescence  —  artificial  light,  of  oil,  lime. . . .  70 

VII.  Phosphorescence —  defined' 70 

1.  Solar  phosphor! ;  substances  affected  by  the  solar  rays 70 

2.  Phosphorescence  from  moderate  heat ;  lime 70 

3.  A nimal  and  vegetable  phosphori 71 

VIII.  Photometers  —  object  and  description  of 71 

Photometer  of  Leslie,  of  Count  Rumford 71 

Sources  of  light ;  similar  to  those  of  caloric 71 

IX.  Nature  of  Light  —  Newton's  theory,  undulatory  theory. ...  71 

CHAPTER  III.  — ELECTRICITY. 

Electricity  ;  mode  of  producing  it 72 

Meaning  of  electrically  excited,  electrified,  cause  of  it 72 


CONTENTS. 


SECT.  1.    COMMON  ELECTRICITY. 


11 


1.  Mode  of  exciting  it  ,  .friction  upon  resinous  bodies 73 

2.  Friction  upon  vitreous  substances  ;  effects  of. 7 

3.  Bodies  electrified  with  each  kind  ;  how  affected  ? 73 

Tlieorics  —  1.  Theory  of  Franklin  ;  positive  and  negative  states. ...  73 
2.  Theory  of  Du  Fay  ;  vitreous  and  resinous,  correspond  to  what'  73 

Inference  from  the  last  theory ;  law  of  each  fluid 74 

Existence  of  the  two  fluids  shown  ;  gold  leaf  electrometer 74 

Non-conductors  ;  defined,  conductors,  do.,  insulators 74 

Electrical  machine  described;  Ills.,  direction  of  currents 75 

Induction  —  defined  and  illustrated,  several  conductors 75 

Theory  of  Induction  —  attraction  and  repulsion  accounted  for 76 

Application  of  the  Theory. 

1.  To  the  spark.     2.  Stroke  of  lightning.     3.  Leyden  jar 76 

4.  Electrophorus  ;   described,  illustrated,  its  use ; 77 

Electrometers  or  Electroscopes  —  object  of 77 

Balance  electrometer ;  described,  uses  of 78 

Laws  of  the  Accumulation  of  the  Electric  Fluid. 

1.  Quantity  of  electricity  on  a  conductor ;  depends  on  what?. .....  78 

2.  Mode  of  distribution  ;  on  a  sphere,  ellipsoid,  effect  of  points. . . .  78 

3.  Tendency  to  escape  from  points  due  to  what  property  ? 78 

4.  Law  of  attraction  and  repulsion  between  two  electrified  bodies..  78 

SECT.  2.     VOLTAIC  ELECTRICITY,  OR  GALVANISM. 

History  —  discovery  of  Galvani,his  theory , 78 

Discovery  of  Volta;  identity  of  galvanism,  magnetism,  etc 79 

I.  Simple  Voltaic  Circles  —  description  of 79 

Direction  of  the  positive  current ;  closed  and  broken  circuit 79 

Different  modes  of  forming  voltaic  circles 80 

Chemical  action  necessary  to  excite  currents  ;  form  of  battery 80 

Calorimotor ;  why  so  called  ? 80 

II.  Compound  Voltaic  Circles — 1.  Voltaic  pile,  described 80 

2.  Best  form  of  the  galvanic  battery  described 81 

Size  and  number  of  plates ;  Hare's  deflagrator 82 

Direction  of  the  currents,  relation  of  electricity  to  chem.  affinity  82 

Tftcuries  of  Galvanism. 

1.  Theory  of  Volta.     2.  Of  Wollaston.     3.  Of  Davy 82 

Laws  of  the  Action  of  Voltaic  Circles. 

Difference  between  quantity  and  intensity 83 

1.  Relation  between  the  exciting  liquid  and  the  zinc 83 

2.  Tension  and  quantity  of  electricity  in  simple  circles 83 

3.  Mode  of  measuring  the  energy  of  voltaic  currents 83 

Decomposing  prtwer ;  power  of  deflecting  magnetic  needle ....   84 

4.  Velocity  of  electricity  through  perfect  conductors 84 

Effects  of  Voltaic  Electricity  or  Galvanism. 

I.  Comparison  of  Common  and  Voltaic  Electricity. 

1.  Action  of  voltaic  electricity  upon  the  gold  leaf  electrometer. . . .  84 

2.  Leyden  jar  charged  by  the  battery  ;  conditions  of 84 

3.  Velocity  of  common  and  voltaic  electricity  ;  effects  of 85 

4.  Tension  of  voltaic  electricity  ;  striking  distance 85 

5.  Effect  of  voltaic  electricity  upon  the  animal  system 85 

6.  Deflection  of  magnetic  needle  and  chemical  decomposition  ....  85 


12  CONTENT*. 

II.  Power  of  Voltaic  Currents  to  ignite  tie  Metals — Illustration  85 
Theory ;  heating  power  of  calorimotor,  and  compound  battery. ...  85 

III.  Chemical  Effects  of  Galvanism  —  history 86 

1.  First  substance  decomposed ;  Illustration 86 

Difference  between  substances  as  ascertained  by  galvanism. ..  87 

2.  Transfer  of  chemical  substances ;  Illustration 87 

Theory  of  Faraday,  of  Davy  ;  electrodes,  anode  and  cathode. . .  88 

Electrolyzed,  electrolyte,  ions,  anions,  and  cations. 89 

Results  of  Faraday's  Investigations. 

1.  Decomposition  by  primary  and  secondary  action 89 

2.  Compounds  which  are  electrolytes 89 

3.  Simple  substances  form  ions 89 

4.  Single  ions  indifferent  to  voltaic  currents 89 

5.  Conditions  for  the  decomposition  of  water .^  89 

6.  Substances  which  form  electrodes '. 89 

7.  Conditions  necessary  to  electro-chemical  decomposition 89 

8.  Conduction  of  electric  currents  in  cells  of  battery 90 

9.  Electro-chemical  equivalents  ;  defined 90 

Faraday's  theory  of  electro-chemical  decomposition 90 

Magnetic  Effects  of  Electricity  or  Electro-Magnetism. 

History ;  discovery  of  Oersted 91 

I.  Influence  of  Voltaic  Currents  upon  the  Magnetic  Needle. 

1,  2,  3,  4,  5.  Position  of  the  needle  in  reference  to  voltaic  currents  91 

6.  Plane  in  which  a  needle  moves  as  related  to  voltaic  currents ...  92 

7.  Electro-dynamic  action  results  from  what  ? 92 

Galvanometers  or  Multipliers ;  Illustration 92 

Revolving  Rectangle  ;  described 94 

II.  Influence  of  Voltaic  Currents  upon  soft  Iron  and  Steel. 

1.  Helix  and  stand ;  description  of 94 

2.  Kind  of  pole ;  dependent  upon  what  ?  Illustration 95 

3.  Electro  magnet ;  what  weight  will  it  sustain  ? 95 

4.  Magic  circle ;  description  and  illustration  of 96 

5.  .Vibrating  magic  circle  ;    description  and  illustration  of 96 

III.  Volta- Electric  Induction  —  Separable  Helices,  described. ..  97 

IV.  Magneto- Electric  Induction  —  denned;  Illustration  ...^...  99 
Magneto-Electric  Machine  described 99 

V.  Theory  of  Electro-Magnetism  and  Magneto- Electricity 100 

Application  of  the  theory ;  magnetism  of  the  earth 101 

VI.  Thermo- Electricity  —  defined  ;  Illustration 102 

VII.  Nature  of  Electricity. 

VIII.  Use  of  Electricity— 1.  Medicinal  Effects 102 

2.  Application  to  the  propelling  of  Machinery 103 

3.  Electro-Magnetic  Telegraph ;  principle  and  description 103 

4.  Electrography ;  Electrotype,  description  of,  theory 104 


PART    SECOND. 
CHEMICAL   AFFIN] 


Cause  of  chemical  changes ;  affinity  defined 105 

Varieties  of  Chemical  Affinity. 

Simple  affinity,  defined,  elective  affinity,  double  elective  affinity  . . .  106 


CONTENTS.  13 

Circumstances  which  modify  Affinity. 

I.  Cohesion  —  opposes  chemical  action,  how  destroyed  ? 107 

1 .  By  pulverization  ;  Illustration 107 

2.  By  solution ;  solvents ;  saturated  solution 108 

Insolubility  ;  its  effect  on  affinity  ;  Illustration 108 

3.  Fusion,  denned,  effect 109 

II.  Elasticity  —  its  effect  on  affinity 109 

1.  Influence  on  decomposition 109 

2.  Effect  of  a  high  temperature  upon  gaseous  mixtures 109 

III.  Quantity  of  Matter  —  its  effect  upon  affinity 109 

IV.  Gravity  —  specific  gravity,  effect 110 

V.  Imponderable  Agents  —  effect  of,  upon  affinity 110 

Measure  of  affinity  ;  how  is  the  force  determined  ?  Illustration ....  Ill 
Effects  of  Affinity. 

I.  Change  of  Chemical  Properties  —  Illustration 112 

II.  Change  of  Color  —  Illustration  ;  dropping  tube 112 

III.  Change  of  Form  —  Illustration  of 113 

IV.  Change  of  Temperature  —  Illustration 113 

V.  Change  of  Specific  Gravity  —  Illustration 113 

Laics  of  Chemical  Affinity. 

I.  Indefinite  Proportions  —  defined ;  how  many  cases  ? 1 14 

II.  Definite  Proportions  by  Weight  —  described 114 

1st  law  ;  mode  of  expressing  the  ratio  of  combination 115 

Standard  of  comparison  ;  equivalent,  meaning  of 115 

Apparent  variations  of  law  ;  Illustration 1 15 

2nd  law ;  constitution  of  each  substance  fixed 116 

Discovery  of  these  laws,  by  whom,  their  use 116 

III.  Definite  Proportions  by  Volume. 

Compared  with  those  by  weight .  / 117 

Atomic  Theory ;  existence  of  atoms 118 

Theory  of  definite  proportions  by  weight ;  Illustrated 118 

Atomic  weight ;  absolute  weight,  magnitude  and  form  of  atoms. . .  118 

Isomerism,  defined,  reconciled  with  definite  proportions 119 

Cause  of  chemical  affinity ;  electricity,  second  causes 119 


PART   THIRD. 

PONDERABLE  BODIES. 

Specific  gravity  ;  defined ;  standard  of  comparison 121 

1.  Method  of  obtaining  specific  gravity  of  solids 121 

2.  do      of  liquids  ;  aerometer,  Illustration.     3.  Of  gases 121 

Nomenclature  —  description  of,  history  of,  uses 122 

1.  Method  of  naming  simple  substances  ;  table  of 122 

2.  Acid  compounds  receive  what  terminations,  prefixes?  etc 123 

3.  Primary  compounds  not  acid  ;  prefixes  and  suffixes. . . .. 124 

Metals  and  alloys ;  hydrates 125 

4.  Secondary  compounds  or  salts;  terminations,  etc 125 

Notation,  defined,  symbols  described,  their  use 126 

Table  of  the  symbols  and  equivalents  of  the  thirteen  non-metallic 
elements,  and  the  symbols  of  their  compounds  with  each  other  127 

^ 


14  CONTENTS. 


CHAPTER  I.  — CHEMICAL  SUBSTANCES. 

CLASS  L     NON-METALLIC  ELEMENTS  AND  THEIR  PRIMARY 
COMPOUNDS. 

SECT.  1.     OXYGEN. 

History  of  discovery ;  natural  history,  process 128 

Pneumatic  cistern,  description  of,  gasometers 129 

Theory  of  process  by  manganese ;  by  chlorate  of  potassa 130 

Physical  and  chemical  properties ;  Illustrated 131 

Effects  of  combustion ;  theory 132 

Oxigenation  and  oxidation ;  relation  of  oxygen  to  animals 133 

SECT.  2.     CHLORINE. 

Symb.  Equiv.  Sp.  gr. ;  history  of  discovery 133 

Natural  history  ;  1.  Process,  theory.     2.  Process,  theory 134 

Physical  and  chemical  properties  ;  Illustrated I  :!•"> 

Relations  to  water,  to  hydrogen  ;  bleaching  effects 1 36 

Relations  to  animals  ;  uses  ;  1.  Bleaching  process,  theory 1  -'-7 

2.  Disinfecting  agency ;  dissecting  rooms ;  diseases  of  skin 138 

Hypochlorous  acid;  Symb.  Equiv.  Sp.  gr.  process,  properties ..  138 

Chlorous,  chloric,  and  perchloric  acids  ;  process,  properties 139 

SECT.  3.     IODINE. 

Symb.  Equiv.  Sp.gr.;  history  of  discovery ;  natural  history  ....  140 

Process  ;  Physical  and  chemical  properties,  tests,  uses 142 

lodic  acid  ;  process,  properties ;  periodic,  and  chloriodic  acids 143 

SECT.  4.     BROMINE. 

Symb.  Equiv.  Sp.  gr. ;  history  of  discovery 143 

Natural  history  ;  process,  physical  and  chem.  properties  illustrated  144 

Bromic  acid;  properties,  chloride  of  bromine;  bromide  of  iodine. . .  145 

SECT.  5.     FLUORINE. 

Symb.  Equiv. ;  natural  history,  properties  as  far  as  known 145 

SECT.  6.     HYDROGEN. 

Symb.  Equiv.  Sp.gr.;  history;  nat.  history,  processes 146 

1.  By  heated  iron  ;  Illustration 146 

2.  By  zinc  and  acidulated  water ;  theory,  impurities 147 

Physical  properties ;  soap  bubbles,  method  of  filling  gas  bags. .  148 

Aerostation  ;  description  of  balloons 149 

Chemical  properties;  illustrated,  theory,  relations  to  animals..  149 

Protoxide  of  hydrogen,  water ;  Symb.    Equiv.  Sp.  gr.,  process. ...  150 

Physical  and  chem.  properties  illustrated,  solvent  properties 151 

Composition,  eudiometer  described ;  compound  blowpipe 152 

Heat  produced  by  blowpipe  ;  binoxide  of  hydrogen,  properties  ....  153 

Hydrochloric  acid  ;  history,  natural  history,  process,  theory 154 

Woulfe's  Appa.,  physical  and  chemical  properties,  illustrated  ....  155 

Constitution  ;  uses  and  impurities 156 

Hydriodic  acid;  Symb.  Eq.  Sp.gr.;  process,  properties,  tests ....  156 

Hydrobromic  acid;  Symb.  Equiv.  Sp.  gr. ;  properties 157 

Hydrofluoric  acid;  history,  process,  theory,  uses  illustrated 157 


CONTENTS.       .  15 

SECT.  7.     NITROGEN. 

Sy mb.  Equiv.  Sp.  gr. ;  history  of  discovery 158 

Natural  history  ;  process,  1.  By  phosphorus 159 

2.  By  sulphur  and  iron.     3.  By  muscle  and  nitric  acid 159 

Theory  of  process  ;  physical  and  chemical  properties 159 

Effect  on  combustion  ;  respiration,  its  nature 159 

Common  air;  physical  properties,  elasticity  illustrated 160 

Pressure  of  the  air ;  how  discovered  ? 160 

Extent  and  composition  of  the  atmosphere 161 

Thetny  of  the  diffusion  of  gases  of  different  sp.  gr.;  Illustrated.  162 

Impurities  of  the  air  ;  eudiometry,  uses  of  the  air 163 

Protttride  of  nitrogen  ;  history,  process,  theory  of,  properties 163 

Respiration  of;  effect  upon  animals 164 

Binoxide  of  nitrogen;  history  of  discovery,  process 164 

Tht-ory  of  process,  properties,  illustrated,  affinity  for  water 165 

1 1 yi>o nitrous  acid ;  properties,  nitrous  acid,  history 165 

Processes,  properties,  respiration  of.     Nitric  acid,  history 166 

Process,  illustrated,  impurities,  properties 167 

Chemical  properties,  illustrated,  uses 168 

J\'itrolnjilrochloric  acid,  aqua  regia ;  nitrohydrojluoric  acid 168 

(Juailrochloride  of  nitrogen  ;  process,  properties 169 

Teriodide  of  nitrogen  ;  Sy  mb.  Equiv.  properties 169 

Ammonia;  history,  process,  theory  of,  properties,  tests,  uses 170 

SKCT.  8.     CARBON. 

Symb.  Equiv.  Sp.  gr. ;   nat.  hist.;  the  diamond,  where  found,  uses  172 

Plumbago,  anthracite,  bituminous  coal,  peat,  and  lamp-black 173 

Charcoal ;  1.  Process  by  slow  combination  of  wood 173 

2.  By  distillation  of  wood.     3.  By  hot  sand 173 

Properties,  hardness,  theory  of  its  absorbing  properties 174 

Clarifying  agency,  combustion  of,  durability  of,  infusibility,  uses  175 

Carbonic  oxide  ;  carbonic  acid,  history  of  discovery 1 76 

Nat.  hist,  process,  theory  of,  relation  to  flame,  to  water 177 

Fermenting  liquors,  best  test  of  carbonic  acid,  solidification  of. ...  178 

Relations  to  animals,  choke-damp 179 

Sources  of  carbonic  acid,  respiration  explained 180 

I    h  oridc,  perchloridc  of  carbon,  Chloro-carbonic  acid,  chloral. . . .  181 

Periodide  and  protiodidc  of,  bromide  of  carbon,  properties 181 

Dirarburet  of  hydrogen  ;  history,  process,  properties.  Illustration..  182 

Olefiunt  gas,  or  2  carburet  of  hydrogen,  Symb.  Equiv.  Sp.  gr 182 

History,  process,  theory  of,  properties,  Ills. ;  action  of  chlorine. . . .  183 

|  Carburet  of  H.  etherine,  3  carburet,  parrijfine,  eupione,  naphtha. .  183 

Naphthaline,  paranaptkaline,  idrialine,  camphene,  and  citrene 184 

Gas  lirrlits ;  history,  process,  portable  gas,  fire-damp 184 

Efforts'of  Davy  ;  discovery  of  Wollaston 186 

Effect  of  gauze  wire  upon  flame  ;  safety  lamp,  construction,  etc. . .  187 

Bicarb  urei'  of  nitrogen  or  ci/anogen,  history,  process,  properties. . .  188 

Cyanic,  fuhninic.  and  cyanuric  acids 188 

Parn  cyan-uric  acid,  chloride,  bichloride,  and  bromide  of  cyanogen.. .  189 

Hydrocyanic  acid.     Process,  properties 189 

SECT.  9.     SUI-PHUR. 

Symb.  Equiv.  Sp.  gr. ;  nat.  hist.,  process  ;  Illus.,  sublimation. ...   190 

Properties,  effect  of  heat,  structure,  impurities,  uses 191 

Hypviulphurous  and  sulphurous  acids,  process,  theory,  crucibles.   192 


16  CONTENTS. 

Hyposulphuric  acid,  process,  properties  ;  sulphuric  acid,  process  . .   194 

Hydrous  sulphuric  acid,  manufacture  of,  theory 195 

Properties,  affinity  for  water ;  Illus.  decomposition,  tests 190 

Uses ;  dichluride,  iodide,  and  bromide  of  sulphur l!>7 

Hydrosulphuric  acid,  process,  theory  of l'.>7 

Properties,  liquid  form,  tests,  uses  ;  Illustration 

Production  of  sulphur;  Illustration;  hydrosvlphurovs  acid !!>!> 

Bisulphuret  of  carbon,  or  alcohol  of  sulphur,  carbosulphuric  acid . .   1 99 

Sulphuret  and  bisulphurct  of  cyanogen 200 

Hydrosulphocyanic  and  cyanohydrosulphuric  acids 200 

SKCT.  10.  •  PHOSPHORUS. 

Symb.  Equiv.  Sp.  gr.  ;  history,  source 200 

Process,  properties,  inflammability ;  Illustrated v 201 

Theory  of  the  heat  and  light,  relation  to  animals. . . .  T 202 

Oxide  of  phosphorus  ;  hypophosphorous  acid 202 

Phosphorous  acid,  process  ;  phosphoric  acids 203 

Phosphoric  acid,  process,  properties  ;  pyro  and  meta  phosp.  acids . .  204 

Sesquic hloride  of  phosphorus,  Symb.  Equiv.,  process,  properties ..  '204 

Perchloride,  protiodide,  sesquiodide,  and  periodide  of  phosphorus  . .  205 

Protobromide,  perbromide,  phosphuret  of  hydrogen,  properties 205 

Perphosphuret  of  hydrogen,  process,  properties,  inflammability  of,  206 

Jack  o'  the  lantern  ;  sulphur  et  of  phosphorus 207 

SECT.  11.     BORON. 

Discovery  ;  process,  property 207 

Boracic  acid;  source,  process,  evaporating  dishes 208 

Tcr chloride  of  boron  ;  fiuoboric  acid,  suphuret  of  boron 209 

SECT.  12.     SELENIUM. 

Discovery,  oxide  of,  seJenious  acid,  properties 210 

Selenic  acid  ;  chloride  and  bromide  of,  hydroselenic  acid 211 

SECT.  13.     SILICON. 

Symb.  Eq.,  discovery,  properties,  silicic  acid,  nat.  history,  process,  212 
Chloride,  bromide,  and  sulphuret  of  silicon,  fluosilicic  acid 213 

'  **• 
CHAPTER    II. 

CLASS  II.    METALS,  WITH  THEIR  PRIMARY  COMPOUNDS. 

General  properties  of  metals,  metallic  lustre 214 

Sp.  gr.  of;  malleability  defined 214 

1.  Ductility,  tenacity.    2.  Hardness.     3.  Structure.    4.  Fusibility  215 

5.  Volatility.     6.  Affinity  for  other  simple  bodies 215 

Combustibility ;  number  and  date  of  discovery 217 

Classification  of  the  metals 217. 218 

ORDER  I.    Metals  which,  by  Oxidation,  yidd  Alkalies  or  Earths. 
SECT.  1.     METALLIC  BASES  OF  THE  ALKALIKS. 

Potassium  ;  history  of  discovery 218 

Process,  properties,  combustibility;  Illustration 219 

Protoxide  of  potassium  ;  properties,  hydrate  of;  Ills.,  tests 220 

Potassa;  teroxide,  iodide, bromide,  fluoride,  and  chloride  of. 221 

Hyduret,  nituret.  sulphurets,  phosphurets  and  seleniuret  of. 222 


CONTENTS.  17 

Cyanuret,  properties  ;  sulphocyanuret  of  .......................  223 

Sodium;  Symb.  Equiv.  Sp.gr  ................................  223 

Process,  properties,  affinity  for  oxygen,  .....................  ...  223 

Protoxide  of  soda,  process  ;  sesquioxide,  chloride  of,  origin,  uses.  224 

Iodide,  bromide,  fluoride,  sulphuret,  and  cyanuret  of  ............  225 

Chloride  of  soda,  alloys  of  sodium  and  potassium  ...............  225 

Lithium  ;  protoxide  of,  or  lithia,  process,  properties,  fluoride  of.  ...  226 

SECT.  2.'  METALLIC  BASES  OF  THE  ALKALINE  EARTHS. 

fsarium  ;  protoxide  of,  or  baryta,  how  distinguished  .............  227 

Uinoxide,  chloride,  iodide,  bromide,  fluoride,  sulphuret  ..........  228 

Cyanuret,  sulphocyanuret,  phosphuret  of  ......................  229 

Strontium  ;  protoxide,  strontia,  peroxide  and  chloride  of.  .........  229 

Iodide  of,  fluoride,  protosulphuret  ............................  230 

Calcium;  protoxide  of,  or  lime,  peroxide,  chloride,  uses;  iodide..  230 

Bromide,  fluoride,  bisulphuret,  phosphuret  of,  chloride  of  lime.  .  .  .  231 

Mti  •!  ni'siiim  ;  discovery,  process,  properties  .....................  232 

Protoxide  of,  or  magnesia,  properties,  uses  .....................  2!>3 

Chloride  of,  iodide,  bromide,  fluoride  ..........................  233 

SECT.  3.     METALLIC  BASKS  OF  THE  EARTHS. 

^Humlniiim;  discovery,  process,  properties,  sesquioxide  of  ........  234 

Scsquichloride,  sesquisulphuret,  sesquiphosphuret  ..............  235 

fjluciniuni  ;  Symb;  Equiv.  Sp.  gr.  ;  discovery,  properties  ........  236 

JSi'squioxide  of,  glucina,  discovery,  process,  properties  ...........  236 

Yttrium  ;  Symb.  Equiv.  ;  process,  properties  ....................  236 

Thorium  ;  bymb.  Equiv.  ;  process,  properties,  protoxide,  do  ......  237 

yrab.  Equiv.  ;  discovery,  process,  properties  ........  237 


ORDER  II.     Metals  the  Oxides  of  which  are  neither  Alkalies  nor 

Earths. 
SECT.  1.     METALS  WHICH  DECOMPOSE  WATER  AT  A  RED  HEAT. 

tMi>i<rintcsc,',  history,  process,  properties,  protoxide  of,  properties  ..  238 
Sc.squ:ox:de,  peroxide,  red  oxide,  varvicite,  manganic  acid  .......  239 

Perchloride,  perfluoride,  protosulphuret,  and  cyanuret,  alloys  .....  240 

Iron;  Symb.  Eq.  Sp.  gr.  :  history,  nat.  history,  process,  properties  241 
Protoxide  of;  process,  properties,  uses,  .....  :  ......  .•  ...........  242 

Peroxide  of;  process,  properties,  etc.  ;  black  oxide,  source,  tests..  243 
Protochloride  ;  perchloride,  protiodide,  properties.  .  .  ;  ...........   243 

Periodide,  protobromide,  perfluoride,  protosulphuret  .............  244 

Sesquisulphuret.  magnetic  iron  pyrites,  tetrasulphuret  ...........  244 

Diphosphuret,  perphosphuret,  carburets,  graphite,  cast  iron,  steel.   245 
Protocyanuret.  protosulphocyanuret,  sesquisulphocyanuret  .......  245 

Zinc;  Symb.  Eq.  Sp.  gr.;  history,  nat.  history,  process,  properties.   246 
Protoxide,  hydrated  oxide,  chloride,  iodide,  bromide,  fluoride,  etc    247 
Cadmium  ;  oxide,  chloride,  iodide,  sulphuret,  and  phosphuret  of.  .   247 
Tin;  process,  properties,  stream  tin,  tin  foil,  protoxide  of  tin  ......  249 

Sesqui  and  binoxide,  proto  and  bichloride,  proto  and  biniodide  of.  .  250 
Protosulphuret,  sesquisulphuret,  bisulphuret,  and  tersulphuret  of.   251 
Cobalt  ;  protoxide,  zafFre-oxide,  and  peroxide  of,  sympathetic  ink.  252 
Protosulphuret,  sesquisulphuret,  bisulphuret,  and  subphosphuretof  253 
Nickel  ;  properties,  protoxide,  sesquioxide,  and  chloride  of.  ......  253 

Protosulphuret,  disulphuret,  subphosphuret,  and  cyanuret  of.  .....  254 

2* 


18  CONTENTS. 

SECT.  2.     METALS  WHICH  DO  NOT  DECOMPOSE  WATER  AT  ANY  TEM- 
PERATURE, AND  THE    OXIDES  OF  WHICH  ARE    NOT    REDUCED   TO   THE 

METALLIC  STATE  BY  THE  SOLE  ACTION  OF  HEAT. 
Arsenic;  discovery,  nat.  history,  fly  powder,  detonations,  uses. . . .   254 

Arsenious  acid  ;  properties,  tests,  poisonous  properties 256 

Arsenic  acid  ;  properties,  protochloride,  and  sesquichloride  of. ...  257 

Periodide,  protohyduret,  and  sesquibromide  of 258 

Arseniureted  hydrogen;  proto,  sesqui,  and  persulphuret  of 258 

Chromium,  properties,  sesquioxide  of;  chromic  acid,  properties...  258 

Sesqui,  terv  and  oxychlorides  of,  sesqui,  and  terfluorides  of. 260 

Sesquisulphuret,  protosulphuret 260 

Vanadium,  proto,  and  binoxide  of;  vanadic  acid,  properties 260 

Molybdenum,  binoxide,  bi,  and  terchloride  of;  molybdic  acid 261 

Tungsten,  binoxide  of;  tungstic  acid,  bichloride  of 262 

Columbium,  binoxide  of;  columbic  acid,  process,  properties 263 

Antimony,  sesquioxide  of;  antimonous  and  antimonic  acids 263 

Sesqui,  and  oxysulphurets  of;  kermes  mineral,  alloys,  pewter. . . .  265 
Uranium  ;  protoxide,  sesquioxide,  prolo,  and  sesquichlorides  of. . .  265 
Cerium;  proto,  and  sesquioxide  of,  proto  and  sesqui  chlorides  of. .  266 
Bismuth  ;  protoxide,  pearl  while,  sesquioxide,  and  chloride  of. ... 

Titanium,  oxide  of;  titanic  acid,  anatase  and  rutile ~<>7 

Tellurium,  oxide  of;  tellurous  acid,  chloride,  sulphurets 

Copper;  nat.  history,  process,  properties,  uses,  red  or  dioxide  of..  i2C>!) 

Black,  or  protoxide  of,  copper  black,  properties,  binoxide  of. 270 

Bichloride,  chloride,  diniodide,  sulphuret,  copper  pyrites,  tests. . . .  270 

Alloys  ;  brass,  Dutch  gold,  pinchbeck,  bell-metal,  bronze '-'To 

Lead  ;  protoxide,  red  oxide,  peroxide,  chloride,  and  iodide  of L'71 

Alloys  of  lead ;  common  pewter,  fine  solder,  pot  metal 271 

SECT.  3.     METALS   THE  OXIDES   OF    WHICH   ARE   REDUCED  TO  THE 
METALLIC  STATE  BY  A  RED  HEAT. 

Mercury  ;  cinnabar,  propeities,  protoxide  of,  properties 273 

Binoxide,  process,  properties;  protochloride,  process,  properties..  274 

Bichloride  of  mercury,  or  corrosive  sublimate,  process,  properties.  274 

Protosulphuret,  bisulphuret,  properties,  cinnabar,  ethiops  mineral.  275 

Bicyanuret  of;  amalgams,  described,  protiodide,  etc 275 

Silver, ;  process,  properties,  cupellation,  uses 276 

Oxide,  fulminating  silver,  torpedoes,  chloride  of. 277 

Iodide,  sulphuret,  cyanuret,  and  alloys  of. 277 

Gold  ;  nat.  history,  process,  quartation,  properties 278 

Protoxide,  binoxide,  and  teroxide  of;  fulminating  gold 279 

Proto,  and  terchlorides  of;  alloys,  water-gilding,  gold  powder....  280 

Platinum;  properties,  spongy  platinum,  proto,  and  binoxide  of. ...  281 

Sequioxide,  protochloride,  bichloride  of 281 

Protiodide,  biniodide,  protosulphuret,  and  bisulphuret  of 282 

Fulminating  platinum,  palladium,  rhodium 282 

Osmium,  osmic  acid,  iridium,  latanium 282 


CHAPTER    III. 

CLASS  III.     SALTS,  OR  SECONDARY  COMPOUNDS. 
SECT.  1.     CRYSTALLIZATION. 

Crystal  and  crystalography  defined 283 

Planes,  faces,  edges,  angles,  primary  and  secondary  forms  of 284 


CONTENTS.  19 

I.  Prisms  have  six-sided  or  four-sided  bases 284 

(1.)  Right  Prisms  —  J .  Hexahedron,  or  cube 284 

2,  3.  Right  square  and  right  rectangular  prisms 284 

4,  5.  Right  rhombic  and  right  rhomboidal  prisms 284 

6.  Regular  hexagonal  prism 285 

(2.)   Oblique  Prisms — 7.  Rhombohedron.     8.     Obi.  rhombic  prism  285 
9.  Oblique  rectangular  prism.     10.  Oblique  rhomboidal  prism ....  285 

II.  Octohedrons  — 11.  Regular  octohedron.     12.  Square  octoh.  285 
13.  Rectangular  octohedrons.     14.  Rhombic  octohedrons 286 

III.  Dodecahedrons  — 15.  Rhombic  dodecahedron 286 

Secondary  forms  ;  cleavage  defined,  faces  and  direction  of 286 

Isomorphism,  crystallogenic  attraction,  water  of  crystallization. . . .  287 

SECT.  2.     OXY-SALTS. 

General  formula  for  the  composition  of  the  salts 288 

1 .  Sul/ihates  —  of  potassa,  soda,  Glauber's  salts 289 

Of  lithia,  ammonia,  baryta,  strontia,  lime,  gypsum 289 

Of  magnesia,  alumina,  manganese,  protoxide  of  iron 291 

Of  protoxide  of  zinc,  (white  vitriol,)  nickel,  cobalt,  chromium. . . .  292 

Of  copper,  (blue  vitriol,)  mercury  (turpeth  mineral,)  silver 293 

Nitro-sulphuric  acid,  sulphate  of  soda,  lime,  potassa,  and  magnesia  294 
Ammonia,  soda,  iron,  chrome,  and  mangan.  alums.     2.  Sulphites  294 

:>.  >\"it.  rates —  of  potassa,  (nitre  beds,)  of  soda,  ammonia 295 

Of  baryta  ;  pyrotechny,  green-fire 296 

Of  strontia,  (red-fire,)  lime,  magnesia,  protoxide  of  copper 297 

Nitrate  and  dmitrate  of  protoxide  of  lead,  of  mercury,  of  silver. ...  297 

Properties,  illustration,  lunar  caustic,  indelible  ink 298 

I .  Nitrites.     5.   Chlorates  —  of  potassa,  properties 299 

Lii  -iti-r  matches,  chlorate  of  baryta,  process,  properties 300 

6.  Perch/orates.     7.   Chlnrites.     8.  Hypochlorites.     9.  lodates 301 

lodate  of  potassa.     10.   Bromatcs.     1 1 .   Phosphates 302 

I.  Phosphates  —  triphosph.,  diphosph.,  and  phosph.  of  potassa  302 
Of  soda  and  ammonia,  ammonia,  Tune,  magnesia,  ainm.  and  mag.  303> 
Triphosphate  of  silver.  —  1 1.  Pyrophosphates 304 

III    Mctaphospkntes —  of  soda,  baryta,  silver,  etc 305 

12.  Jlrseniates ;  of  soda,  table  of  compounds 305 

13.  Jrsenitts ;  general  properties,  tests 306 

14.  Chromates;  of  potassa,  lead.     15.  Borat.es;  of  soda,  borax.. ..  307 

16.  Carbonates ;  of  potassa,  soda,  ammonia 308 

Of  baryta,  strontia,  lime,  magnesia 310 

Of  iron,  copper,  lead,  white  lead,  mercury 311 

17.  Double  Carbonates 312 

18.  Silicates ;  simple,  bi,  tri,  and  quadri  silicates 312 

SECT.  3.  ORDER  II.  HYDRO-SALTS  ;  acids  of 314 

SECT.  4.  ORDER  III.  SULPHUR-SALTS;  constitution  of. 316 

SECT.  5.  ORDER  IV.  HALOID-SALTS;  constitution  and  descrip.  of  319 


CHAPTER  IV,  — NATURAL  SUBSTANCES. 

ORGANIC  CHEMISTRY. 

Nature  of  organic  compared  with  inorganic  compounds 321 

Decomposition  of,  formation  of;  relation  to  inorganic  bodies 322 

VEGETABLE  CHEMISTRY. 

Proximate  principles,  proximate  analysis,  ultimate  analysis 322 

Results  of  Wfthler,  Liebig,  Pelouse,  and  Dumas 323 


20  CONTENTS. 

1.  Amides,  or  .imidets ;  theory,  meaning  of  oxamide  and  amide. ..  323 

2.  Benzoyl;  theory.     3.  Ethers;  theory,  radical  of  the  ethert 323 

4.  Pyracids  ;  theory.     5.   Theory  of  substitutions;  dehydrogenizing  3:23 
SECT.  1.  VEGETABLE  ACIDS  ;  general  properties,  description  of. ..  323 
SECT.  2,  VEGETABLE  ALKALIES  ;  constitution  and  description  of  332 
SECT.  3.  NEUTRAL    SUBSTANCES;  constitution  and  description  of  334 

SECT.  4.  OILS  ;  fixed  and  volatile  oils  described 337 

SECT.  5.  SPIRITUOUS  AND  ETHEREAL  SUBSTANCES  ;  description  of  341 

SECT.  6.  COLORING  MATTERS  ;  lakes,  dyes,  etc 3-13 

SECT.  7.  FERMENTATION  ;  saccharine,  vinous,  putrefactive 345 

SECT.  8.  GERMINATION  ;  growth  and  food  of  plants 347 

CHAPTER  V.  — ANIMAL  CHEMISTRY. 

SECT.  1.  PROIIM.  PRINCIPLES  NEITHER  ACID  «OR  OLEAGINOUS.  . . .  349 
SECT.  2.  ANIMAL  ACIDS  ;  general  principles  and  description  of. ...   349 

SECT.  3.  ANIMAL  OILS  AND  FATS  ;  description  of 350 

,SECT.  4.  COMPLEX  ANIMAL  SUBSTANCES;  blood, chyle, etc 351 

CHAPTER  VI.  — ANALYTICAL  CHEMISTRY. 

SECT.  1.     ANALYSIS  OF  MIXED  GASES. 

1 .  Gaseous  mixtures  containing  oxygen 356 

2.  Gaseous  mixtures  containing  nitrogen 3;»7 

3.  Gaseous  mixtures  containing  carbonic  acid 357 

4.  Gaseous  mixtures  containing  hydrogen  and  other  infl'le  bodies  357 

SECT.  2.     ANALYSIS  OF  MINERALS  AND  METALLIC  ORES. 

I.  Analysis  of  minerals  soluble  in  acids,  with  effervescence 357 

II.  Analysis  of  minerals  insoluble  in  acids 358 

III.  Analysis  of  minerals  containing  carbonate  of  lime 358 

Silica,  oxide  of  iron  and  magnesia : . . . .   3.>H 

IV.  Tests  of  the  metallic  ores 35!» 

1 .  Ores  of  antimony.     2.  Of  lead.     3.  Of  mercury 35!) 

4.  Ores  of  zinc.    5.  Of  tin.    (5.  Of  iron.    7.  Of  copper.    8.  Of  silver  359 
9.  Ores  of  gold  and  platinum ;  earthy  sulphates 359 

SECT.  3.     ANALYSIS  OF  MINERAL  WATERS. 

1.  Rain  water.     2.  Well  and  spring  water.    3.  Acidulous  springs.  360 

4.  Alkaline  springs.     5.  Chalybeate  and  saline  springs 360 

6.  Sulphureted  springs  ;  detection  of  hydrosulphuric  acid 361 

Test  tubes ;  filtration ;  filtering  process ;  supports 361 

APPENDIX;  Wollaston's  synoptic  scale  of  chemical  equivalents.. .  364 

Cementing ;  various  cements 3 

GLOSSARY 373 

GENERAL  INDEX 385 

INDEX  OF  PLATES 396 


NOTE. 

F.  and  Fahr.  for  Fahrenheit's  thermometer.  —  T.  refers  to  Turner's  Chemistry.— 
W.  to  Webster's  Chemistry,  3rd  Ed.  —  L.  to  Liebig.  —  B.  to  Berzelius.  —  Eq.  and 
Equiv.  for  Equivalent.  -  Symb.  for  Symbol  or  formula. 


INTRODUCTION. 


SCIF.M'E  is  classified  knowledge.  Physical  or  Natural 
Science  is  the  knowledge  of  the  material  world.  The  defi- 
nition of  matter  embraces  two  properties,  without  which  we 
cannot  even  conceive  of  its  existence.  These  properties  are 
cftiiision,  which  includes  length,  breadth,  and  thickness,  and 
impenetrability,  or  the  impossibility  that  any  two  portions  of 
matter  should  occupy  the  same  space.  There  are  other  prop- 
erties, which  do  not  necessarily  enter  into  our  conception  of 
matter,  but  which  universally  belong  to  it,  such  as  gravitation, 
inertia,  mobility,  etc. 

Natural  Science  consists  of  three  great  branches,  whi(dl 
are  characterized  chiefly  by  peculiar  methods  of  investigation. 

I.  NATURAL  PHILOSOPHY  employs  the  method  of  general 
;;'/j/>/r.s ;  th'it  is,  it  observes,  for  example,  the  gravitation  of  a 
stone  let  fill  to  the  ground,  and,  neglecting  the  other  proper- 
ties of  the  stone,  observes  the  same  property  in  other  bodies, 
and  generalizes  the  phenomena  under  a  law.  It  is  therefore 
conversant  with  general  laws,  but  not  with  all  the  general 
laws,  for  its  observation  is  restricted  to  the  phenomena  of 
pn-n  ptibln  di<tanr.c.  By  this  we  mean  that  it  leaves  to  the 
chemist  all  those  phenomena  which  arise  from  the  action  of 
the  invisible  atoms  of  muter  upon  each  other,  and  attends 
only  to  those  which  belong  to  bodies  of  perceptible  size. 
With  a  few  observations  and  experiments  for  data,  it  depends 
for  discovery  upon  calculation,  and  its  character  is  therefore 
eminently  mathematical.  Its  object  is  a  knowledge  of  the 
laws  of  motions  and  forces. 


INTRODUCTION. 

II.  CHEMISTRY  employs,  in  part,  the  method  of  general 
physics,  and,  in  part,  the  method  of  particular  physic.*.  By 
the  latter,  we  mean  that  its  object  is,  in  part,  to  describe 
particular  bodies  or  substances,  by  giving  an  account  of  the 
various  properties  of  each  one,  before  calling  the  attention  to 
another.  It  invites  our  attention  to  the  phenomena  only  of 
imperceptible  distance.  With  some  aid  from  calculation  and 
observation,  it  depends  for  discovery  chiefly  upon  experiment, 
and  has  therefore  been  called  Experimental  Philosophy.  Its 
object  is  a  knowledge  of  the  constitution  of  substances  and 
of  the  phenomena  attending  a  change  of  constitution. 

IH.  NATURAL  HISTORY  employs  the  method  of  particular 
physics,  observes  the  phenomena  of  perceptible  distance,  and 
depends  for  discovery  chiefly  upon  observation,  with  some  aid 
from  experiment  and  calculation.  Its  object  is  a  knowledge 
of  natural  objects.  It  embraces  Zoology,  or  the  stutfy  of 
animals;  Botany,  or  the  study  of  plants;  Mineralogy,  which 
treats  of  minerals ;  and  Geology,  which  describes  and  accounts 
for  the  condition  of  the  crust  of  the  earth.  The  physiology 
d§  plants  and  animals  is  sometimes  referred  to  Botany  and 
Zoology  respectively,  and  sometimes  regarded  as  a  fourth 
distinct  branch  of  Natural  Science. 

Plan  of  the  Work. 

I.  The  constitution  and  the  changes  of  the  constitution 
of  substances  are  intimately  connected  with  the  agency  of 

Jieat,  light,  electricity,  and  galvanismyvof  which  the  two  Inst- 
mentioned  agents  are  now, known  to  be  identical.  Whether 
these  agents  are  themselves  substances^  or  mere  properties 
of  matter,  is  not  certainly  known.  ^They  have  no  appreciable 
weight^  and  are  therefore  called  imponderable  agents.  They 
will  form  the  subject  of  the  First  Part. 

II.  The  Second  Part  will  treat  of  fhetniccrl  affinity. :  This 
is  the  great  agent  to  which  all  the  phenomena  of  chemistry  are 
referred.     It  is  distinguished  from  gravitation  by  exerting  its 
force  between  the  particles  of  bodies,  and  from  cohesion  by 


INTRODUCTION. 

acting  only  between  particles  of  different  kinds  or  in  different 
states  of  electricity.  For  example,  a  block  of  marble  is  made 
up  of  very  small  particles,  each  one  of  which  is  similar  to  the 
whole;  but  each  of  these  particles  is  composed  of  two  others, 
carbonic  acid  and  lime,  different  from  each  other,  and  from 
marble.  When  these  particles  of  carbonic  acid  and  lime  are 
brought  into  close  proximity  to  each  other,  they  assume  dif- 
ferent electrical  states,  and  combine  by  the  force  of  chemical 
(iffiuity,  and  form  particles  of  marble.  ACohesionAthen  attaches 
them  to  each  other  as  fast  as  formed,  and  thus  the  block  is 
formed.  /pravity/%acts  upon  it  in  the  mass.  The  carbonic 
acid  and  the  lime  are  called  thejoinptmritt  particles,*  When 
these  combine,  they  form  the ;  tntrffrantf  particles.  Hence 
Chemistry  is  denned  to  be  that  science  the  object  of  which  is, 
to  examine  the  relations  which  affinity  establishes  between 
bodies,  ascertain  with  precision  the  nature  and  constitution  of 
the  compounds  it  produces,  and  determine  the  laws  by  which 
its  action  is  regulated. 

It  is  the  object  of  Natural  Philosophy  to  examine  the  sen- 
sible motions  and  mutual  relations  of  bodies  in  masses,  con- 
sequent upon  gravity. 

^Chemistry  investigates  the    constitution   and  qualifies  of 
bodies  as  they  stand  related  to  chemical  affinity^ 

III.  The  Third  Part  will  comprise  a  description  of  sub- 
stances, which  will  be  arranged  in  two  general  divisions  :  The 
first  will  embrace  the  elements  and  those  compound  sui> 
stances  which  can  be  formed  in  the  laboratory.  These  are 
chemical  substances.  The  second  division  will  embrace 
natural  substances,  or  animal,  vegetable,  and  mineral  com- 
pounds, which  have  been  formed  by  natural  agencies. 

Chemists  divide  substances  into  simple  and  compound.  A 
simple  substance  is  one  which  never  has  been  separated  into 
two  kinds  of  matterv$or  which  has  never  been  decomposed./, 
There  are  about  fifty-four  simple  substances.  A  compound 
body(  is  one  which  is  composed  of  two  or  more  simple  bodies, 
of  which  there  are  many  thousands. 


,24  INTRODUCTION. 

The  composition  of  bodies  is  ascertained  by  two  methods : 

1.  /By  separating  the  body  into  its  simple  elements,  which 
is  called  analysis  ;t  and, 

2.  By  causing  the  elements  to  combine  and  form  the  body, 
which  is  called  synthesis.^ 

Chemical  substances  are  arranged  in  three  general  di- 
visions : 

I.  Non-metallic  elements,  and  their   primary  compounds 
with  each  other. 

II.  Metals,  and  their  primary  compounds. 

III.  Salts,  or  secondary  compounds. 

In  the  arrangement  of  the  simple  substances  and  their 
primary  compounds,  the  logical  order  is  pursued ;  that  is, 
after  describing  one  substance,  the  rest  are  described  with  the 
compounds  which  they  form  with  those  previously  described. 

The  Salts  are  divided  into  four  orders : 

I.  Ozy~saltst  or  those  salts  the  acid  or  base  of  which  is  an 
oxidized  substance. 

II.  Hydro-salts.     This  order  includes  no  salt,  the  acid  or 
base  of  which  does  not  contain  hydrogen. 

III.  Sulphur-salts,   or  those   salts,   of  which  the  electro- 
positive or  electro-negative  ingredient  is  a  sulplutnt. 

IV.  Haloid-salts,  including  none,  the  electro-positive  or 
electro-negative  ingredient  of  which  is  not  haloidal,   i.  e., 
analogous  in  composition  to  sea  salt. 


CHEMISTRY 


PART    I. 

IMPONDERABLE    AGENTS. 

VI 

CHAPTER  I.  — CALORIC. 

THE  word  heat  has  two  meanings,  ^t  is  the  sensation  whici 
we  experience  when  we  touch  a  hot  body/t  or  it  is  the  caust- 
of  the  sensation.  In  the  first  sense,  it  is  an  effect  producer 
onhy  upon  animals.  In  the  second,  it  is  the  cause  of  a  grea' 
variety  of  effects  in  the  mineral,  vegetable,  and  animal  king- 
doms. The  word  caloric  (Lat.  calor)  is  used  in  the  latter 
sense.  Where  there  can  be  no  ambiguity,  the  word  heat  is 
often  retained  in  the  same  sense.  Caloric  exists  in  a  free 
or  sensible,  and  in  a  latent  or  insensible  state. 

1.  Sensible  Caloric.    In  this  state,  caloric  is  capable   of 
producing  the  sensation  of  heat,  and  of  expanding  bodies. 
It  has   sometimes   been   called   the  caloric   of  temperature. 
Temperature  expresses  the  power  of  exciting  the  sensation, 
and  is  proportioned  to  the  quantity  of  free  caloric.     A  high 
temperature  is  owing  to  a  great  quantity,  and  a  low  temper- 
ature to  a  small  quantity. 

2.  Insensible  Caloric.    In  this  condition,  caloric  produces 
no  sensation,  but  exists,  often  in  great  quantity,  in  substances, 
without  affecting  their  temperature,  and  appears  to  be  com- 
bined with  them. 

3 


i2t>  Conduction  of  Caloric. 

SECT.  1.     SENSIBLE  CALORIC. 
Communication  of  Sensible  Caloric. 

The  most  important  property  of  free  caloric  is  its  tendency 
to  an  equilibrium;  that  is,  a  tendency  to  escape  from  hotter 
to  colder  bodies,  so  as  to  produce  in  all  the  same  degree 
of  temperature.  This  communication  takes  place  in  two 
ways —  by  conduction,  and  by  radiation. 

I.  Conduction.  By  this  is  meant  the  passage  of  caloric 
through  a  body,  from  panicle  to  particle. 

i-rimfnt.  Place  bits  of  phosphorus  alon<;  an  iron  rod,  and  apply 
heal  to  one  eiui  <>f  it;  the  progress  of  the  caloric  will  be  indicated  by 
its  igniting  the  phosphorus. 

The  property  in  the  body,  on  which  this  transmission 
depends,  is  called  the  conducting  power. 

If  one  end  of  an  iron  rod  be  held  in  the  fire,  the  sons-it  inn 
ofhoat  will  so.m  bo  experienced  at  the  other  extremity,  in 
consequence  of  the  conduction  of  caloric  from  particle  to 
particle  along  the  rod.  If  the  rod  be  of  glass  it  will  he 
much  longer  before  any  heat  is  felt.  Hence  different  sub- 
stances conduct  caloric  irith  different  degrees  of  facility. 

If  two  bodies  are  in  contact,  caloric  may  be  conducted 
from  one  to  the  other.  ij|e  more  permit  the  contact,  otlvr 
things  being  equal,  the  more  rttjnd  the  conduction.  This 
is  the  reason  why  a  heated  body,  when  grnsppd  firmly  by  t!i» 
hand,  will  burn  it  more  -  :un  when  held  loosely. 

The  contact  of  two  solids  with  each  other,  or  of  a  solid 
with  a  gas,  is  not  so  perfect  as  that  of  a  solid  with  a  liquid  ; 
and  hence  the  communication  is  more  rapid  in  the  latter 
C:IM\  When  liquids  are  mixed  with  liquids,  or  gases  with 
gases,  the  contact  is  still  more  perfect,  and  the  caloric  is 
more  rapidly  diffused  through  the  whole. 

From  the  two  f.ict>  which  have  been  mentioned,  it  follows 
that  the  rapidity  of  conduction  from  a  heattd  to  a  cold  body 
depends  upon  the  conducting  power  of  each  substance,  and 
the  closeness  of  conta.t. 


Conducting  Poircr  of  Sot,  27 

Plunge  a  heated  iron  into  cold  water,  and  again,  equally  heated, 
into  mercury.  In  the  latter  ease,  it  will  cool  more  rapidly  ;  lor,  while 
the  heat  is  with  equal  facility  in  b.-tii  cases  from  the  interior 

to  the  surfaee.  it  is  taken  from  the  surfaee  mure  rapidly  by  the  mercury 
than  by  the  water. 

tereury  two  equal  balls,  one  of  iron  and  the  othei 

Be  temperature.     The  iron  Imll  will  cool  the 

more  rapidly,  because  the  caloric  is  more  freely  conducted  from  its  in 

-  surface. 

Plunjje  the  iron  hall  into  mercury,  and  the  marble  into  water. 
The  iron  \\ilfcool  more  rapidly,  for  two"  reasons;  the  heat  will  come 
to  its  surface  more  freely,  and  be  taken  otf  by  the  mercury  more 
rapidly,  iron  and  mercury  being  each  better  conductors  than  marble 
or  water. 

Of  the  dillerent  forms  of  matter,  'solids  are  better  conduct- 
ors of  caloric  than  //\/«/c/.«,  and  liquids  than  gu- 

1.    Conducting  Power  of  Solids.    This  power  varies  greatly 
in  different  solids. 

This  fact  may  be  shown  by  Fig.  1. 

the  conditctonntrr,  (Fig.  1,)  []  _  f]  |]  _  []  II  (l.fl 
which  consists  of  a  tin  or  iron 
.  in  which  there  may  be 
inserted  small  solid  cylinders  of 
the  same  dimensions,  but  of 
different  materials.  A 

/:.r/>.    Place  upon  one  end  of  each,  bits  of  phosphorus,  and  apply  to 
the  «,i  her  ends  the  sai.ie  decree  of  heat  by  placing  the  case  over  boil  in  | 

water       The   oal  >rie    will    be   e.«»ndueted    alon^r   |rom  one   extremity  of 
rru-h  ;  .  and  tii-  substance  which  conducts  most  rapidly  will 

,'iite  the  phosphorus. 

irr  to  the  experiments  of  M.  Despretz,  if  the  con- 
power  of 

(iold   be  represented  by  1000  Tin    .    . 

Siher  will  be      .     .     ."    973  Lead    .    . 

Copper S<H.\J  Marble  . 

Platinum :':>1  Porcelain 

Iron 374.3  Fine  clay  .   11.4 

//me      .  .... 


IIIIIIIIIOIllll 


Metals  generally  are  the  best  conductors  of  caloric,  while 
furs  and  porous  substances  are  the  poorest  conductors. 

The  conductiiur  power  of  stones  is  next  to  that  of  the 
metals,  and  crystal  line  stones  are  better  conductors  than  the 

uncryst  illized. 


.  28  Caloric  —  Conducting  Power  of  Liquids. 

The  earths  generally  are  bad  conductors.  Bricks,  glass, 
dry  wood,  charcoal,  conduct  less;  and  feathers,  silh  hair, 
and  down,  least  of  all. 

Among  the  latter,  the  finer  tfojibre,  the  less  its  conducting 
power.  Hence  the  utility  of  fine  wool  and  furs  in  the  winter, 
to  prevent  the  escape  of  caloric  from  the  body  ;  while,  in  the 
summer,  we  select  those  substances  for  our  clothing  which 
have  a  coarser  fibre.  In  this  we  see  the  benevolence  of  God 
in  furnishing  those  animals  which  inhabit  the  colder  regions 
of  the  earth,  with  finer  clothing  than  those  which  inhabit 
warm  climates.  The  fur  of  animals  is  also  finer  in  whiter 
than  in  summer. 

Snow  and  ice  are  poor  conductors ;  and  hence,  by  a  wise 
constitution,  the  earth  in  winter  is  rarely  frozen  to  any  con- 
siderable depth.  The  ice  and  snow  keep  it  warm  by  pre- 
venting its  vital  heat  frora  escaping. 

The  conducting  powers  of  solids  are  generally  in  the  ratio 
of  their  densities;  especially  of  the  same  ..substance.  In- 
crease of  density  will  increase  the  conducting  power,  and 
vice  versa. 

2.  Conducting  Power  of  Liquids.  In  liquids  the  conduct- 
ing power  is  much  less  than  in  solids.  So  feeble  is  it,  that 
some,  among  whom  is  Count  Rumford,  have  denied  its  ex- 
istence. But,  notwithstanding  the  slight  conducting  power 
of  liquids,  heat  can  be  diffused  through  them  much  more 
rapidly  than  through  solids.  This  is  effected  by  a  motion 
among  the  particles,  which  brings  them  successively  into 
contact  with  the  heated  surface. 

If,  for  example,  heat  is  applied  to  the          Fig.  2. 

^bottom  of  a  vessel  of  water,  (Fig.  2,)  those 
particles  of  water  which  are  in  contact 
with  the  bottom,  are  soon  heated,  and  con- 
sequently expanded  and  made  lighter,  so 
that  they  are  forced  to  rise,  in  order  to  give 
place  to  the  heavier  cold  particles,  which 
fall  to  the  bottom.  The  latter,  in  turn,  are 
heated,  and  give  place  to  others ;  and  thus 
the  process  continues  until  two  currents 
are  established,  the  one  of-heated  particles 
rising  to  the  surface,  and  the  other  of  colder  particles  falling 
to  the  bottom.  In  this  way  all  the  water  is  soon  heated  by 


Conducting  Power  of  Gases.  29 

direct  contact  with  the  bottom.*  A  little  powdered  auiber  or 
gum  copal,  put  into  the  water,  will  indicate  the  direction 
of  the  currents. 

But  if  heat  be  applied  to  the  top  of  the  ves-          F»S-  3. 
sel,  the  water  at  the  bottom  will  remain  cold, 
while  that  at  the  top  is  boiling. 

Erp.  Suspend  in  a  tin  cup  a  hot  cannon  ball  on  the 
top  of  a  jar  of  water,  (Fig.  3,)  at  the  bottom  of  which  is 
a  piece  of  ice.  The  water  will  boil  npidly  at  the  top, 
while  the  ice  remains  umuelied.  But  if  the  ice  is 
phc.ed  upon  the  top,  and  heat  applied  to  the  bottom, 
the  ice  will  all  be  melted  before  the  water  can  be 
made  to  boil. 

Erp.  Or,  burn  ether  (Fig.  4)  on  the  top  of  a  glass 
fnnin -1  filled  with  water,  into  which  an  air  thermome- 
ter is  cemented.  The  thermometer  will  not  be  sensibly 
affected.  A  ring  of  tin  should  be  phced  on  the  top  of 
the  water,  within  half  au  inch  of  the  sides  of  the  fun- 
nel ;  and  the  ether,  poured  within  this  ring,  will  burn, 
without  the  risk  of  breaking  the  ghiss. 

It  has,  however,  been  shown  that  liquids  do 
conduct  heat,  independently  of  any  intestine 
motion.  Cut  the  power  is  very  slight. 

3.  Conducting  Pawn-  of  Gnats.  Gases  and  vapors  conduct 
heat  very  slightly,  if  at  all.  Their  particles  move  with  so 
much  facility  when  heated,  that  it  is  difficult  to  arrive  at  any 
satisfactory  results  on  this  subject.  Heat  may  be  diffused 
through  them  in  the  same  manner  as  through  liquids,  but 
with  much  greater  rapidity. 

II.  Radiation.  If  a  heated  body  be  suspended  in  the  air, 
its  caloric  will  be  diffused  both  by  the  currents  of  air,  which 
circulate  to  and  from  its  surface,  and,  in  a  slight  degree,  by 
the  conducting  power  of  the  air.  But  if  the  hand  be  placed 
beneath  the  heated  body,  a  sensation  of  heat  will  be  perceived, 
which  is  not  due  to  either  of  these  causes,  but  to  the  direct 
passage  of  the  rays  through  the  air. 

For  if  a  heated  body  be  suspended  in  a  vacuum,  entirely 
removed  from  conducting  substances,  it  will  rapidly  cool 

*  A  Florence  flask,  or  a  glass  tube,  may  be  used  for  this  experiment, 
and  the  water  heated  by  a  common  tin  lamp  filled  with  alcohol. 
3  * 


30 


Radiation  of  Caloric 


down  to  the  same  temperature  with  surrounding  bodies. 
Caloric,  which  is  thus  thrown  off  from  heated  bodies  in  all 
directions,  like  rays  of  light  from  the  sun,  is  called  radiant 
caloric. 

1.  If  a  thermometer   be   placed   at  the  distance   of  two 
inches  from  a  heated  body,  it  will  be  affected  but  one  fourth 
as  much  as  at  the  distance  of  one  inch ;  if  it  be  placed  at  the 
distance  of  three  inches,  one  ninth  as  much  ;  if  at  four  inches, 
one  sixteenth  as  much ;  at  five  inches,  one  twenty-fifth,  etc. 
Hence,  in  consequence  of  a  radiation  in  all  directions,  the 
intensity  of  the  heat  is  in  the  inverse  ratio  of  the  square  of 
the  distance.     The  intensity  of  light  and  the  force  of  gravi- 
tation follow  the  same  law. 

2.  The  degree  of  radiation,  and  consequently  the  intensity 
of  radiant  heat,  are  greatly  modified  by  the  kind  of  surface. 
Bright,  polished  surfaces  do  not  radiate  so  rapidly  as  those 
which  are  dark  and  rough. 

Fig.  5. 

6 


Exp.  Take  a  square 
tin  cup,  a,  (Fig.  5,)  one 


suit1  of  which  is  bright, 
another  rough,  a  third 
painted  black,  and  the 
fourth  painted  white. 
Fill  it  with  hot  water, 
and  bring  an  air  ther- 
mometer, c,  near  each 
side.  The  rough  and 
black  surfaces  will 
radiate  more  rapidly 
than  those  which  are 
white  and  polished. 

If  the  rays  of  caloric  are  brought  to  a  focus  by  the  mirror  A,  the  dif- 
ferent degrees  of  caloric  from  the  several  surfaces  will  be  much  more 
evident.* 

The  greater  radiating  power  of  rough  surfaces  is  supposed 
to  be  due  to  the  great  number  of  radiating  points;  or  perhaps 

*  The  late  experiments  of  Melloni  do  not  seem  to  confirm  this  view. 
By  using  a  cup  of  marble,  whose  external  surfaces  were  differently 
prepared,  the  first  polished,  the  second  smooth  but  tarnished,  the  third 
streaked  in  one  direction,  and  the  fourth  in  two,  crossing  each  other  at 
right  angles,  and  filling  the  vessel  with  hot  water,  each  of  the  sides 
projected  the  same  quantity  of  radiant  caloric.  —  Edin.  Philos.  Jour 
X&VL  299. 


Reflection  of  Caloric. 


31 


it  may  be  owing  to  the  greater  amount  of  surface  exposed 
within  a  given  space. 

3.  The  rapidity  of  radiation  also  depends  upon  the  differ- 
ence between  the  temperature  of  the  radiating  body  and  that 
of  the  surrounding  bodies.  Hence,  with  a  given  temperature 
of  the  latter,  the  higher  the  temperature  of  the  radiating  body, 
the  more  rapid  the  radiation.  * 

III.  Disposition  of  radiant  Caloric.  Radiant  caloric  passes 
in  right  lines  through  a  vacuum,  through  air  and  gases,  with- 
out any  apparent  obstruction;  but  when  it  falls  upon  solid  or 
liquid  substances,  it  is  disposed  of  in  three  ways:  1.  It  re- 
bound:, from  the  surface,  or  is  reflected.  2.  It  enters  into  the 
substance,  or  is  absorbed.  3.  It  passes  through  the  body,  or 
is  transmitted. 

1.    Reflection  of  Caloric.     When  radiant  caloric  falls  upon 

bright,  polished  surfaces,  it  is  mostly  reflected  in  lines,  which 

form  angles  with  a  perpendicular  to  the  reflecting  surface, 

!  to  the  angles  formed  by  the  same  perpendicular,  and 

the  lines  in  which  the  rays  went  to  the  surface. 

Thus,  let  BAG  (Fig.  6)  be  a  smooth  sur-  Fig.  6. 

f '( •«',  S  the  incident  ray,  P  the  perpendicular 
to  the  surface,  and  R  the  reflected  ray.  The 
angle  RAP  is  equal  to  the  angle  PAS.  The 
angle  PAS  is  called  the  angle  of  incidence, 
and  PAR  the  angle  of  reflection.  Light  fol- 
lows the  same  law.  If  a  concave  surface  be 
used,  the  rays  of  caloric  will  be  reflected  and 
brought  to  a  focus.  This  may  be  shown  by 
two  metallic  mirrors,  as  in  Fig.  7.  a  and  b 

Fig.  7. 


32  Absorption  of  Caloric. 

are  two  reflectors  of  polished  metal,  (brass  or  tin,)  12  inches 
in  diameter,  and  segments  of  a  sphere  of  9  inches  radius. 
Place  them  at  any  convenient  distance  apart,  from  6  to  12 
feet.  If  a  heated  ball  of  iron  be  placed  in  the  focus  of  or,  and 
an  air  thermometer  in  that  of  6,  the  caloric  will  first  radiate 
to  the  surface  of  a,  and  then  he  reflected  in  parallel  lines  to 
the  surface  of  6,  whence  the  rays  will  be  reflected  to  the  focus 
in  which  the  bulb  of  the  thermometer  is  placed,  and  will 
cause  the  liquid  to  descend,  showing  an  increase  of  tempera- 
ture. If  phosphorus  be  placed  in  the  focus,  it  will  be  ignited. 
If  snow  be  substituted  for  the  heated  ball,  the  thermometer 
will  show,  by  the  rise  of  the  liquid,  a  diminution  of  tempera- 
ture. As  bright,  polished  surfaces  reflect  most  of  the  calorific 
rays  which  fall  upon  them,  we  can  see  the  reason  why  they 
are  not  easily  heated. 

2.  Absorption  of  Caloric.    When  radiant  caloric  falls  upon 
rough,  opaque  substances,  it  is  mostly  absorbed ;  that  is,   it 
passes  directly  into  the  substance,  and  renders  it  hot :  some 
of  the  rays  are  also  reflected. 

The  power  of  absorption,  as  well  as  of  radiation  and  re- 
flection, depends  mostly  upon  the  surface.  Those  surfaces 
which  reflect  most,  radiate  and  absorb  least,  and  those  which 
radiate  and  absorb  most,  reflect  least.  The  power  of  absorp- 
tion and  that  of  radiation  are  equal ;  and  as  each  increases, 
the  power  of  reflection  diminishes. 

The  color  of  the  surface  also  affects  the  power  of  absorp- 
tion. Dr.  Stark  has  shown  that  black  surfaces,  other  things 
being  equal,  absorb  the  most ;  dark  green  next  to  black ; 
scarlet  next ;  and  white  the  least  of  all  colors. 

Exp.  This  fact  may  be  shown  by  placing  strips  of  cloth  of  different 
colors  upon  snow,  exposed  to  the  sun's  rays ;  the  black  will  be  found 
to  sink  into  the  snow  to  the  greatest,  and  the  white  to  the  least,  depth, 
because  the  black  absorbs  the  rays  which  melt  the  snow,  and  the  white 
reflects  them.  Hence  the  advantage  of  painting  rooms  white,  or  of 
whitewashing  them  :  the  rays  of  caloric  are  thus  kept  passing  from 
side  to  side,  without  being  absorbed  and  conducted  away. 

3.  Transmission  of  Caloric.     When  radiant  caloric  falls 
upon  the    surface  of  transparent  solid  or  liquid    bodies,  it 
passes  through  them  in  a  slight  degree. 

It  passes  easily  through  air  and  other  gaseous  substances, 
without  sensibly  affecting  them;  but  glass  and  crystalline 


T/icories  of  Radiation.  33 

pnbstances  intercept  most  of  the  rays.  Prof.  Leslie  contends 
tint  glass  does  not  permit  the  rays  to  pass  directly  through  it, 
but  absorbs  them  at  one  surface,  and  transmits  them  to  the 
other  by  conduction,  from  which  they  are  again  radiated. 
This  opinion  is  supported  by  Dr.  Brewster  by  an  argument 
drawn  from  his  optical  researches.  But  the  experiments  of 
Do  la  Roche  lead  to  a  different  conclusion  —  that  the  calorific 
rays  do  pass  through  glass,  although  slowly.  This  opinion  is 
supported  by  other  chemists. 

The  radiant  caloric  which  is  associated  with  solar  light 
passes  readily  through  glass  and  other  transparent  bodies. 
The  caloric,  in  this  case,  seems  to  be  modified  by  its  con- 
nection with  light,  and  may  be  collected  into  a  focus  with  trie 
light,  as  in  the  case  of  a  burning-glass.  Caloric,  thus  asso- 
ciated, suffers  refraction  in  passing  from  one  medium  to 
another,  and  in  general  is  subject  to  the  same  laws  with  light 

IV.  Theories  of  Radiation.  Of  the  various  theories  to 
account  for  radiation,  only  two  seem  worthy  of  notice. 

1.  The  theory  of  Pictet  supposes  that   a  hot  body  will 
radiate  caloric  to  surrounding  colder  bodies,  until  the  equi- 
librium is  restored,  and»then  cease. 

2.  The  theory  of  Prevost  supposes  that  all  bodies,  what- 
ever  be  their  temperature,  are  constantly  giving   out    and 
receiving  radiant  caloric.     When  a  body  is  giving  out  more 
r  iys  than  it  is  receiving,  it  is  cooling.     When  it  gives  and 
receives  an  equal  number,  its  temperature  remains  stationary, 
and    is   in   equilibrium  with  surrounding  bodies.     When  it 
receives  more  rays  than  it  gives  off,  its  temperature  is  in- 
creasing.    On  this  theory,  all  bodies  —  the  polar  ice,  as  well 
as  the  burning  sands  of  the  tropics  —  are  constantly  radiating 
and  absorbing  caloric. 

Although  most  of  the  phenomena  of  radiation  may  be 
explained  on  both  theories,  preference  is  generally  given  to 
that  of  Prevost.  The  ground  of  this  preference  is  found  in 
the  close  analogy  between  the  laws  of  light  and  heat.  It  is 
well  known  that  luminous  bodies  continually  exchange  rays. 
A  feeble  light  sends  rays  to  one  of  greater  intensity,  and  the 
quantity  of  rays  emitted  by  each  does  not  seem  to  be  affected 


34  Application  of  the.   Theory  of  Prcvost. 

by  the  vicinity  of  other  luminous  bodies.     In  like  manner  all 
bodies  are  supposed  continually  to  exchange  rays  of  caloric. 

V.  Application  of  the  Theory  of  Prcvost  to  the  Explana- 
tion of  various  Phenomena. 

1.  In  the  experiments  with  the  mirrors,  if  the  ball  in  the 
focus  of  one  mirror  is  of  the  same  temperature  with  the 
thermometer    in  that  of  the  other,    and    with   surrounding 
objects,  the  thermometer  will  remain  stationary,  because  it 
receives  from  the  ball  the  same  quantity  of  rays  which  it 
sends  to  it;  but  if  the  temperature  of  the  ball  be  raised  above 
that  of  the  surrounding  objects,  the  thermometer  will  receive 
more  rays  than  it  imparts,  and  will  consequently  show  an 
increase  of  temperature.  ^If  ice  be  substituted  for  the  ball, 
the  thermometer  will  show  a  diminution  of  temperature,  be- 
cause it  gives  out  more  rays  than  it  receives. 

When  ice  is  placed  in  the  focus  of  a  mirror,  there  is  an 
apparent  radiation  of  cold.  But  on  this  theory  it  is  easily 
explained,  and  is  what  might  be  expected  previous  to  experi- 
ment.* Cold  is  a  negative  term,  merely  expressing  the 
absence,  in  a  greater  or  less  degree,  of  caloric. 

2.  The  formation  of  dew  depends  upon  radiation,  and  is 
satisfactorily  accounted  for  on  this  theory.    The  earth,  during 
the  day,  becomes  heated  by  absorbing  the  sun's  rays,  and  the 
moisture  is  driven  off  into  the  air.     During  the  night,  it  radi- 
ates more  caloric  than  it  receives,  and  becomes  colder  than 
the  surrounding  atmosphere.    Successive  strata  of  air  charged 
with   moisture,    come    in    contact  with  the  earth,  and    the 
moisture  is  condensed  in  the  form  of  dew. 

The  quantity  of  dew  will  therefore  depend  upon  the  radi- 
ating power  of  the  surface,  and  the  quantity  of  moisture  in 
the  air ;  the  more  rapid  the  radiation,  the  more  dew  will  be 
formed.  There  is  more  dew  upon  grass  and  leaves  than 
upon  stones;  and  the  thermometer  will  sink  15°  or  20°  lower, 
when  placed  upon  grass,  than  when  suspended  in  the  air,  or 
laid  on  polished  surfaces.  In  India,  ice  is  formed  by  ex- 
posing water  in  pans  in  a  clear  night,  when  the  temperature 

*  See  Turner,  Gth  edition,  p.  13,  note 


Cooling  of  Bodies.  35 

of  the  air  is  never  down  to  the  freezing  point.  But  why  is 
there  no  dew  in  a  cloudy  night?  Because  the  clouds  reflect 
back  the  radiant  caloric  to  the  earth,  which  therefore  cannot 
become  cooler  than  the  air.  In  a  clear  night,  there  is  no 
such  interchange  of  rays,  and  the  caloric  passes  off  into  the 
regions  of  space.* 

VI.  Cooling  of  Bodies.     The  cooling  of  a   hot  body  is 
effected  in  two  ways,  already  noticed.     When  surrounded  by 
solid    bodies  in  contact  with  it,  the  heat  is  carried  off  by 
conduction,  and  the  velocity  of  cooling  will  depend  upon  the 
conducting  power.     When  the  heated  body  is  immersed  in 
liquids,  the  same  is  true  to  some  extent,  although  much  de- 
pends  upon  the  mobility   of  the  particles.     But  when  sur- 
rounded by  gases,  the  cooling  takes  place  by  means  of  con- 
duction and  radiation,  and  in  a  vacuum,  by  radiation  alone. 

Velocity  of  cooling  means  the  number  of  degrees  lost  in  a 
given  time.  Law  of  cooling  refers  to  the  relation  which  the 
velocities  of  equal  successive  periods  bear  to  one  another. 
The  higher  the  temperature,  other  things  being  equal,  the 
greater  the  velocity.  If  a  body  heated  to  1000°  lose  100° 
during  the  first  second,  Newton  inferred  that  it  would  lose 
TV°f  tne  remainder,  or  90°,  during  the  next  second,  81*  the 
next,  72.9°  the  next,  and  65.6°  the  next.  These  numbers 
form  a  geometrical  series,  whose  ratio  is  1.111 ;  and,  though 
the  law  is  not  universal,  it  holds  true,  when  the  temperature 
is  but  a  little  elevated  above  the  air. 

VII.  Practical  Application  of  the  Laws  of  Conducted  and 
Radiant  Caloric.     The  material  for  windows  should  be  a  bad 

•  conductor  of  heat,  as  well  as  transparent ;  hence  glass  is  best 
adapted  to  the  purpose.  Glass  also  admits  solar  heat,  while 
it  prevents  the  escape  of  artificial  heat.  Double  walls,  doors, 
and  windows,  add  to  the  warmth  of  buildings,  because  they 
confine  between  them  a  stratum  of  air,  which,  when  not  in 
motion,  is  a  good  non-conductor.  Snow,  furs,  woollens,  etc., 
are  better  non-conductors,  because  they  enclose  air.  Stoves 
which  are  rough  radiate  more  heat  than  those  which  are 

*  The  quantity  of  dew  seems  to  depend  also  upon  the  difference  be- 
tween the  temperature  of  the  atmosphere  and  that  of  the  earth. 


36  Effects  of  Free  Caloric. 

polished.  As  the  temperature  of  the  human  body  usually 
exceeds  that  of  the  atmosphere,  the  object  of  clothing  in 
cold  weather  is  to  retain  the  natural  warmth ;  and  hence  it 
is  made  of  good  non-conductors.  In  hot  weather,  clothing 
should  conduct  off  the  heat  more  freely.  Also,  under  a  hot 
sun,  a  black  dress  is  more  uncomfortable  than  one  of  light 
color.  Many  articles  employed  in  the  common  uses  of  life 
are  selected  with  reference  to  their  conducting  and  radiating 
properties,  as  materials  for  furnaces,  culinary  apparatus,  etc. 

Effects  of  Free  Caloric. 

The  phenomena  which  may  be  ascribed  to  caloric  as  an 
agent,  and  which  may  therefore1  be  classified  as  its  effects, 
are  numerous  :  some  of  these  effects  will  now  be  enumerated. 

The  most  remarkable  property  of  caloric,  as  we  have  seen, 
is  the  repulsion,  which  exists  among  its  particles,  by  which 
it  tends  to  an  equilibrium,  or  to  bring  all  substances  to  the 
same  degree  of  temperature.  This  property  enables  it  to 
penetrate  all  bodies,  and,  by  its  accumulation,  to  separate  the 
integrant  molecules  from  each  other.  It  thus  acts  in  oppo- 
sition to  cohesive  attraction ;  hence  it  may  be  stated  as  a 
general  law,  that 

I.  Caloric  expands  all  bodies;  liquids  more  than  solids, 
and  gases  more  than  either. 

1.  Caloric  expands  solids.     This  may  be  shown  by  fitting 
an  iron  cylinder  to  an    aperture,   so    that  it  will  just  slide 
through;  heat  it,  and  it  will  be  too  large  to  pass  through. 

2.  Equal  degrees  of  caloric  expand  some  solids  more  than 
others.   -This   may   be   shown   by  an    instrument   called    a 
pyrometer,  or  fire  measurer. 

Fig.  8  represents  this  instrument.  It  is  furnished  with 
several  rods,  as  iron,  brass,  copper,  lead,  and  glass. 

BB,  posts  standing  in  A,  and  secured  from  spreading  apart 
by  the  two  bars  CC.  G,  a  thumbscrew, .passing  through  the 
post  B,  and  entering  one  end  of  the  rod  D,  holds  it  against 
a  lever  at  the  other  end ;  as  the  rod  is  heated,  it  expands  and 
presses  against  the  lever,  which  raises  E,  at  the  end  of  which 
is  a  cord  passing  up,  over  the  hub  of  the  index,  and  down 


Expansion  of  Solids. 


37 


again  to  the  balance  rod  F ;  E  is  raised  by  the  expansion  of 
the  rod  D ;  F  falls,  drawing  the  cord,  and  giving  motion  to  the 

hand. 

Fie.  8. 


The  following  substances,  when  heated  from  32°  to  212° 
Fahr.,  are  elongated  as  follows:   * 

its  length. 


Flint  glass,      ....     T2V* 

Iron,     ....     ..V 

Copper,      ..... 

Brass,    ...... 

Lead      .     .      .    '.     .     . 


3.  Equal  increments,  or  additions  of  caloric,  at  different 
temperatures,  do  not  expand  the  same  solid  equally. 

That  is,  the  expansion  of  a  brass  or  iron  rod  will  be  much 
greater  between  500°  and  600°,  than  between  100°  and  200°, 
or  than  between  200°  and  300°.  The  higher  the  tempera- 
ture, the  greater  the  expansion,  with  equal  additions  of 
caloric.  This  results  from  the  fact  that  the  power  of  cohe- 
sion is  constantly  diminished,  the  farther  the  integrant  parti- 
cles are  removed  from  each  other  by  heat. 

4.  The  expansion  of  some  solids  is   more  uniform  than 
others,  with  equal  additions  of  caloric.     The  expansions  of 
the  more  infusible  solids  are  uniform  within  certain  limits. 
From  32°  to  122°,  their  expansion  is  equal  to  that  between 

4 


38 


Expansion  of  Liquids. 


122°  and  212°.     But  above  212°,  the  higher  the  temperature, 
the  greater  the  expansion,  for  equal  additions  of  caloric. 

II.  Caloric  expands  liquids  more  than  solids. 

1.  This  fact  may  be  illustrated  by  heating  a 
column  of  water  in  a  glass  tube,  and  an  iron  rod 
of  the  same  dimensions,  by  a  spirit  lamp ;  the  water 
will  rise  in  the  tube,  while  the  iron  will  scarcely  be 
affected.      The  reason  is,  that   the   cohesive   at- 
traction in  liquids  is  nearly  destroyed. 

Exp.  Plunge  a  common  thermometer  into  a  jar  of  hot 
water,  (Fig.  9.)  The  bulb  of  the  thermometer  will  be  ex- 
panded, and  its  capacity  increased,  but  the  mercury  will 
be  more  expanded,  and  will  rise  in  the  tube. 

Fig.  10. 

2.  Equal  increments  of  caloric  ex- 
pand some   liquids  more  than  others. 
This   may  be    illustrated  by  partially 
filling   several    glass   tubes    furnished 
with  bulbs  with  different  liquids,  and 
placing  them  in   hot   water;    as   the 
liquids  expand,  they  will  rise    to  dif- 
ferent heights  in  the  tubes,  as  shown 
in  Fig.  10. 

3.  Equal  additions  of  caloric,  at  different  tempt <-raturrtt 
do  not  expand  the  same  liquids  equally.     The  same  law  holds 
here  as  in  the  case  of  solids — the  higher  the  temperature,  the 
greater  the  expansion  for  equal  amounts  of  heat;  and  those 
liquids  also*  which  expand  the  least  are  more  uniform  within 
certain  limits.     Apparent  exceptions  to  the  general  law  .-.re 
found  in  the  case  of  some  liquids,  near  the  point  of  con- 
gelation.    Water  expands  by  a  diminution  of  temperature, 
and  contracts  by  an  addition  of  caloric,  between  the  freezing 
point  and  40°  Fahr. 

III.  Caloric    expands    gases    more   than 
solids  or  liquids. 

1.  The  expansion  of  air  may  be  shown  by 
simply  inverting  a  glass  tube  terminated  by  a 
bulb,  and  partly  filled  with  water,  (Fig.  11,) 
in  a  vessel  of  the  same  liquid  :  on  heating  the 
bulb,  the  air  will  expand,  and  expel  the  liquid 
from  the  tube ;  or  by  holding  a  bladder  partly 


Fig.  11. 


Expansion  of  Gases.  39 

filled  with  air  near  the  fire,  the  air  will  soon  expand,  fill  the 
bladder,  and  even  burst  it.* 

2.  All  gases,  at  any  temperature,  are  expanded  equally 
h :/  <  (jual  additions  of  caloric.  In  this  respect,  gases  differ 
from  solids  and  liquids.  If,  therefore,  we  can  ascertain  the 
expansion  of  one  gas  for  a  given  number  of  degrees,  we  may 
know  that  of  all  others.  The  law  of  the  expansion  of  air 
has  been  determined  by  Gay  Lussac,  who  found  that  a  given 
quantity  of  dry  air  dilates  to  ^bv  of  the  volume  it  occupied 
at  32°,  for  the  addition  of  each  degree  of  Fahr. 

Tluonj  of  Expansion.  This  has  been  already  noticed.  In 
the  case  of  solids,  the  integrant  particles  are  held  together 
by  cohesive  attraction,  but  the  caloric,  being  self-repellent, 
has  the  'effect  to  overcome  this  force,  and  to  separate  the 
particles  from  each  other. t  In  case  of  liquids,  cohesive  at- 
traction is  much  more  feeble ;  it  will  therefore  require  less 
power  to  separate  the  particles,  and  hence  they  are  more 
expansible  than  solids.  Gases  are  still  less  under  the  influ- 
ence of  cohesion,  and  hence  are  more  expansible.  In  fact, 
the  form  which  matter  assumes  seems  to  depend  upon  the 
relative  force  of  caloric  and  cohesion.  In  solids,  cohesion 
preponderates ;  in  gases,  caloric ;  but  in  perfect  liquids,  these 
forces  are  in  equilibrium,  (the  caloric  being  in  a  combined, 
and  not  a  sensible  state.) 

IV.  Apparent  Exceptions.  Allusion  was  made  to  water 
and  some  other  substances  as  apparent  exceptions  to  the 
general  law  that  heat  expands  and  cold  contracts  all  bodies. 
Water  continues  to  contract,  until  it  arrives  at  39°,  and  then 
begins  to  expand  until  congelation  takes  place. 


*  So  great  is  the  tendency  of  air  and  other  gases  to  expand,  that,  if 
a  given  portion  be  confined  in  a  bladder,  or  in  a  very  thin  glass  of  a 
square  form,  and  put  under  the  exhausted  receiver  ofan  air  pump,  the 
5a:ne  effect  will  be  produced  as  when  heat  is  applied;  the  particles  of 
gases  seem  to  be  wholly  free  from  the  influence  of  cohesive  attraction, 
and  expand  by  their  own  caloric  when  the  pressure  is  removed. 

t  On  the  supposition  that  caloric  is  material,  the  effect  is  easily  ac- 
counted for;  but  though  &s  particles  repel  each  other,  they  must  have 
a  strong  attraction  fur  matter,  or  they  could  not  be  introduced  into  it. 
Caloric,  therefore,  is  the  antagonist  force  to  cohesive  attraction,  but 
possesses  a  powerful  attraction  for  matter,  peculiar  to  itself. 


40  The  Force  of  Expansion. 

Exp.  Take  a  glass  tube,  with  a  bulb  at  one  end,  fill  it  with  warm 
water,  and  place  it  in  a  mixture  of  salt  and  enow.  The  water  in  the 
tube  will  sink  until  it  arrives  at  39°,  and  then  begin  to  rise  until  it 
arrives  at  32°.  The  water,  in  becoming  ice,  will  increase  in  bulk  £» 
and  ice,  in  melting,  will  diminish  in  bulk  y^}  hence,  if  the  specific 
gravity  of  water  is  10,  ice  will  be  9.  The  maximum  density  of  water 
is  at  39°  Fahr. 

V.  The  force  of  expansion,  when  water  freezes,  is  very 
great.     The  Florentine  academicians  burst  a  hollow  brass 
globe,  whose  cavity  was  only  one  inch  in  diameter,  by  freez- 
ing the  water  contained  in  it.     This  must  have  required  a 
force  equal  to  27,720  pounds.     Major  Williams,  in  ITH-l-S, 
performed  similar  experiments  at  Quebec,  by  bursting  bombs, 
which  also  illustrated  the  amazing  force  of  water  in  the  act 
of  congelation. 

In  consequence  of  this  expansive  force,  glass  and  earthen 
vessels  are  broken,  by  suffering  water  to  freeze  within  them  ; 
water  pipes  are  burst;  pavements  are  thrown  up,  and  de- 
.stroyed,  and  walls,  especially  in  moist  grounds,  thrown 
down. 

Theory.  The  cause  of  this  expansion  is  supposed  to  be 
due  to  crystallization.  The  particles,  at  39°,  seem  to  be 
endowed  with  a  kind  of  polarity,  and  attract  the  edges  of 
each  other ;  and,  at  32°,  they  are  arranged  in  ranks  and  files, 
which  cross  at  angles  of  60°  and  120°,  as  may  be  seen  when 
water  is  freezing  in  a  saucer.  This  new  arrangement  of  the 
particles  is  supposed  to  increase  the  bulk ;  but,  whether  this 
hypothesis  be  correct  or  not,  it  seems  best  to  explain  the 
effect.* 

VI.  Advantage  of  this  Exception.     The  wisdom  and  be- 
nevolence of  God  are  strikingly  exhibited  in  this  arrange- 
ment.    Otherwise,  all  our  rivers,  and  lakes,  and  the  ocean 
itself,  in  cold  climates,  would  become  solid  masses  of  ice ! 

When  a  body  of  water  is  freezing,  there  are  two  currents 

*  This  hypothesis  relieves  us  from  the  necessity  of  supposing  a  real 
exception  to  the  laws  of  nature.  The  effect  is  due  to  the  operation  of 
another  law,  (crystallization,)  to  which  the  law  of  expansion  gives 
place.  For,  after  the  crystallization  is  completed,  the  usual  law  pre- 
vails, and  ice  contracts,  with  the  further  reduction  of  temperature.  Fis- 
sures are  thus  produced,  in  extreme  cold  weather,  by  the  contraction 
of  ice  on  ponds. 


Uses  of  the  Law  of  Expansion.  41 

established,  as  in  the  case  of  boiling  water.  The  surface 
gives  off  its  caloric  to  the  air,  and  the  particles  become  heavy, 
and  sink  down.  -  This  forces  the  warm  particles  below  to 
rise.  But  at  39°  these  currents  are  arrested,  because  the 
colder  particles  begin  to  expand,  and  remain  at  the  top.  As 
soon  as  they  are  frozen,  a  covering  of  ice  prevents,  in  a  great 
measure,  the  escape  of  caloric  from  beneath,  and  the  process 
of  freezing  is  greatly  retarded.  But,  if  the  contraction  ex- 
tended to  the  freezing  point,  the  colder  particles  would  con- 
tinue to  fall  to  the  bottom,  until  the  whole  should  be  brought 
to  that  point,  and  then  suddenly  freeze ;  or,  if  they  should 
freeze  upon  the  surface,  the  ice  would  continue  to  sink  down 
until  the  whole  should  become  a  solid  mass. 

I  fence,  in  coif  climates,  the  rivers  and  lakes  would  be 
converted  into  solid  ice,  and  all  their  inhabitants  would  be 
destroyed  !  But,  by  this  simple  and  beautiful  arrangement, 
the  ice  is  retained  upon  the  surface,  and  confines  sufficient 
stores  of  caloric  to  preserve  the  inhabitants  of  the  waters,  and 
render  the  coldest  climates  habitable  by  man. 

Water  is  not  the  only  liquid  which  expands  under  the 
reduction  of  temperature;  as  the  same  effect  has  been  ob- 
served in  a  few  others,  which  assume  a  highly  crystalline 
structure,  on  becoming  solid.  Hence  the  exactness  with 
which  cast  iron  fills  the  mould,  and  the  use  of  antimony  in 
casting  types.  Mercury  is  a  remarkable  instance  of  the  re- 
verse ;  for,  when  it  freezes,  it  suffers  a  very  great  contrac- 
tion. 

VII.  Practical  Uses  of  the  general  Law  of  Expansion  and 
Contraction.  All  kinds  of  machinery  are,  of  course,  affected 
by  this'  law.  It  must  be  strictly  regarded  in  the  construction 
of  delicate  time-pieces.  Great  use  is  made  of  it  in  the  band- 
ing of  wheels ;  the  iron  is  heated,  and  fitted  to  the  dimen- 
sions, and  then  suddenly  cooled,  so  that,  by  its  contraction, 
it  presses  with  great  force,  and  becomes  immovably  fixed. 
In  riveting  together  iron  plates  for  steam  engine  boilers,  it  is 
necessary  to  produce  as  close  a  joint  as  possible.  This  is 
effected  by  using  the  rivets  red-hot ;  the  contraction,  which 
the  rivet  undergoes  in  cooling,  draws  the  plates  together 
with  a  force  which  is  only  limited  by  the  tenacity  of  the 
metal  of  which  the  rivet  itself  is  made. 

M.   Molard,  a  few  years   since,  at  Paris,  availed  himself  of  this 

4* 


42  Thermometers. 

principle,  to  restore  to  their  perpendicular  direction  two  opposite  walls 
of  a  gallery,  which  had  been  pressed  outward  by  incumbent  weight. 
Through  holes  in  the  walls,  several  strong  iron  bars  wt-re  introduced, 
so  as  to  cross  the  apartment,  with  the  ends  projecting ;  upon  which 
strong  iron  plates  were  screwed.  The  bars  were  then  heated,  and, 
while  hot,  the  plates  were  screwed  up.  On  cooling,  the  bars  con- 
tracted, and  drew  the  walls  together.  By  repeating  this  process  several 
times,  they  were  restored  to  their  original  position.  Balloons  were 
first  sent  up  filled  with  air  which  had  been  expanded  by  heat. 

Winds.  The  phenomena  of  winds  depend  upon  the  expan- 
sion of  the  air  by  the  heat  of  the  sun.  In  this  way  the  trado 
winds  are  produced.  Land  and  sea  breezes  depend  upon  radi- 
ation and  expansion.  During  the  day,  the  earth  is  more 
heated  than  the  water,  and  the  air  is  more  expanded,  and 
rises  up.  This  will  produce  currents-a-fl^pold  air  from  the 
water  to  the  land,%called  sea  breezes.  During  the  night,  the 
earth  radiates  caloric  more  rapidly  than  the  water,  the  air  be- 
comes cooler,  and  currents  pass  from  the  land  to  the  water, 
which  are  called  land  breezes.  Winds  are  also  produced  in 
those  deserts  which  become  greatly  heated  during  the  day. 

T/tcrmometers.  But  one  of  the  most  ingenious  and  useful 
applications  of  this  law  is  to  be  found  in  the  thermome- 
ter. Its  invention  is  'generally  ascribed  to  Sanctorius,  who 
flourished  in  the  seventeenth  century.  Some  ascribe  it  to 
Cornelius  Drebel,  and  others  to  Galileo. 

1.  Air  Thermometers.  The  substance  employed 
by  Sanctorius  was  atmospheric  air,  by  the  expan-  Fig:.  12. 
sion  and  contraction  of  which  he  was  enabled  to  (~} 
measure  variations  of  temperature.  His  plan  was 
very  simple.  The  instrument  consists  of  a  glass 
tube,  (Fig.  12,)  open  at  one  end,  with  a  ball  blown 
at  the  other ;  enough  of  some  colored  liquid  is 
poured  in  to  fill  half  the  tube,  which  is  then  in- 
verted in  a  vessel  of  the  same  liquid.  The  air  in 
the  bulb,  by  its  expansion,  causes  the  water  in  the 
tube  to  sink,  and,  by  its  contraction,  the  pressure  of 
the  atmosphere  causes  it  to  rise.  By  adapting  a 
scale  to  the  tube,  the  instrument  is  fitted  for  use.* 

On  one  account,  air  is  the  best  substance  for  a  thermometer, 

*  This  instrument  is  easily  constructed  by  heating  a  glass  tube  in 
the  fire,  and  blowing  a  bulb  upon  the  end;  then  insert  the  open  end  in 
•ome  colored  liquid. 


Differential  Thermometer.  43 

because  its  expansions  and  contractions  are  equal,  with  equal 
additions  of  caloric.  But  there  are  two  objections  to  the  use 
of  this  instrument ;  —  it  can  be  depended  upon  only  when  the 
barometer  stands  at  a  fixed  point;  variations  of  atmospheric 
pressure  materially  affect  the  rise  or  fall  of  the  liquid.  The 
expansion  of  gases,  also,  with  slight  degrees  of  caloric,  is  so 
great,  that  the  length  of  the  tube  for  measuring  high  or  low 
temperatures  would  render  the  instrument  inconvenient  in 
practice. 

2.  Differential  Thermometer.  Sir  J.  Leslie,  in  1804,  con- 
structed a  thermometer,  in  which  air  is  used,  which  is  not 
affected  by  atmospheric  pressure. 

It  consists  of  two  glass  balls,  (Fig.  13,) 
joined  together  by  a  glass  tube,  bent  twice 
at  ri:_rht  angles.  The  balls  contain  air,  but 
the  tube  is  nearly  filled  with  sulphuric  acid, 
CDlored  with  carmine.  To  one  leg  of  this 
t'.i'x'  is  applied  a  scale  It  is  evident  that  no 
effect  will  be  produced  upon  the  liquid,  if 
both  balls  are  heated  alike,  because  the  air 
in  both  will  suffer  equal  expansion;  but  the 
slightest  difference  between  the  temperature 
of  the  two  balls,  will  instantly  be  indicated  by 
the  rise  or  fall  of  the  Kquid  in  the  tube. 
Hence  its  only  use  is  to  detect  slight  variations  of  tempera- 
ture between  two  substances,  or  of  two  contiguous  spots  in 
the  same  atmosphere,  in  very  delicate  experiments,  where 
caloric  is  reflected,  or  refracted  to  a  focus.  It  is  hence  called 
the  Differential  Thermometer. 

A  much  more  delicate  instrument  of  this  kind  has  been 
constructed  by  Dr.  Howard,  of  Baltimore,  in  which  the  vapor 
of  ether,  or  alcohol,  in  vacua,  is  used  instead  of  air. 

But  if  air  expands  too  much,  and  is  affected  by  pressure,  so 
as  to  be  unfitted  for  the  common  purposes  of  measuring  the 
degrees  of  temperature,  solid  substances,  on  the  other  hand, 
expand  too  little. 

The  substance  most  convenient  is  a  liquid,  and  the  object 
is,  to  find  some  liquid  whose  dilations  are  nearly  equal  with 
equal  additions  of  caloric,  and  whose  boiling  and  freezing 


44  Mercurial  Thermometer.  f 

points  are  removed  at  the  greatest  distance  from  each  other. 
Alcohol  and  ether  would  answer  this  purpose  very  well  in 
one  respect,  —  they  resist  congelation  to  a  very  low  tempera- 
ture, but  boil  much  sooner  than  water.  Mercury  seems  to  be 
the  only  substance  which  will  answer  the  necessary  condi- 
tions. 

3.    Mercurial    Thermometer.     This    instrument    Fig.  14. 
(Fig.  14)  is  constructed  in  the  following  manner : 
A  tube  is  selected  with  a  small  bore,  of  uniform 


diameter,  and  a  small  ball  is  blown  at  one  end. 
The,air  is  then  mostly  expelled  from  the  bulb,  by 
holding  it  in  a  spirit  lamp,  and  the  end  of  the  tube 
quickly  inverted  in  a  cup  of  clear,  dry  mercury. 


As  the  bulb  cools,  the  atmosphere  forces  the  mer- 
cury into  the  bulb,  which  fills  it  two  thirds  full ; 
the  bulb  is  again  heated,  and  the  mercury  rises  up, 
nearly  filling  the  tube,  and  expelling  the  air.  It  is 
again  inverted  over  mercury,  when  the  bulb  and 
one  third  of  the  tube  are  filled ;  it  is  then  heated 
until  it  boils,  and  fills  the  tube  to  the  top.  A  fine  (lame  is 
then  darted  from  a  blowpipe  *  upon  the  open  extremity  of 
the  tube^  so  as  to  fuse  the  glass,  and  clo;je  the  aperture 
before  the  mercury  recedes.  It  is  then  said  to  be  her nut i- 
cally  sealed,  and  the  space  abandoned  at  the  upper  extremity 
of  the  tube,  as  it  cools,  is  a  vacuum. 

N. 

Graduation.  This  is  effected  by  ascertaining  two  fixed  points  ;  and, 
as  water  always  freezes  at  the  same  temperature,  and  also  boils  at  tin- 
same  temperature,  when  the  barometer  stands  at  the  same  height,  we 
have  only  to  immerse  the  bulb  and  a  part  of  the  stem  in  melting  snow, 
or  water  containing  ice,  and  mark  the  point  to  which  the  mercury 
sinks.  This  is  the  freezing  point.  To  fix  the  boiling  point,  distilled 
water  should  be  used,  and  the  barometer  should  stand  at  30  inches. 
A  small  quantity  of  the  water,  not  more  than  one  inch  in  depth,  and 
contained  in  a  deep  metallic  vessel,  is  made  to  boil  briskly,  and  the 
point  to  which  the  mercury  riees,  is  marked  ;  this  is  the  boiling  point. 
These  two  points  being  fixed,  the  interval  is  variously  divided  into 
equal  parts. 


Fij? 

*  Fig.  15'  represents  the  most  common  forms 
of  the  blowpipe.  It  consists  of  a  brass  or  Copper 
tube,  tapering  nearly  to  a  point,  through  the  small 
end  of  which  the  air  is  forced,  either  by  placing 
the  large  end  in  the  mouth,  or  by  adapting  to  it  a 
pair  of  bellows. 


Register   Thermometer. 


46 


Newton  first  suggested  a  scale,  in  which 
the  zero  was  placed  at  the  freezing  point, 
and  the  interv.il  divided  into  40  parts,  or 
degrees.  In  Fahrenheit's  thermometer, 
which  is  generally  used  in  this  country  and 
in  England,  the  zero  is  placed  at  32°  below 
the  freezing  point,  and  the  interval  between 
the  freezing  and  the  boiling  points  is  divided 
into  180  parts,  so  that  the  boiling  point  of 
water  is  212°.  Fahrenheit  fixed  his  zero 
by  immersing  the  thermometer  in  a  mixture 
of  snow  and  salt.  Reaumur's  scale  places 
the  freezing  point  at  zero,  and  the  boiling  at 
80°.  De  Lisle  placed  the  boiling  point  at 
zero,  and  the  freezing  at  150°  below  ;  this 
is  used  in  Russia.  But  the  most  convenient 
scale  is  that  of  Celsius,  in  which  the  freez- 
ing point  is  at  zero,  and  the  boiling  at  100°, 
called  the  Centigrade  thermometer;  this  is 
used  in  France.  The  different  scales  are 
seen  in  Fig.  16. 

The  scale  is  either  marked  on  the  tube 
by  a  diamond,  or  on  ivory  or  paper,  and  at- 
tached to  the  tube.  The  degrees  above  the 
boiling  and  below  the  freezing  points  occupy 
o(ju;il  spaces  w-th  those  between  these  points. 
The  temperature  expressed  by  one  scale  can 
be  reduced  to  that  of  another,  by  knowing 
the  relation  which  exists  between  their  de- 
grees. The  lower  part  of  the  scale,  in  labo- 
ratory thermometers,  (Fig.  14,)  turns  up  by 
a  hinge,  so  that  the  bulb  can  be  immersed 
in  corrosive  liquids. 


Fig.  10. 


J  Fahrenheit. 

|  Centigrade. 

J  Reaniniir. 

Tl 

J  De  Lisle. 

710- 

Jt 

_ 

*<>•  " 

=  •90 

;,' 

[0 

: 

-.  : 

,_, 

. 

Go 

I 

/'j 

- 

50 

140 

"  •£*• 

;o 

- 

GO  _ 

MO- 

76'  ; 

BO- 

r-40 

.90- 

loo-  • 

to 

80- 

;i 

y.j- 

70 

1.^0 

12D-- 

60 

C(V 

tin 

Tff 

U; 

•'-, 

-  _ 

V 

~ 

-         Q 

_r, 

-- 

_ 

: 

-    10 

• 

R 

55 

r  - 

- 

Fig.  17. 


4.     Register    Yjfurmomfter, 

This    instrument    consists    of 

two  thermometer  tubes,  (Fig. 

17,)  bent  at  right  angles,  and 

retaining  a  horizontal  position. 

One  tube  contains  alcohol,  and 

the  other  mercury.     A  small  piece  of  black  enamel  is  placed 

in  the  tubes  on  the  surface  of  each  liquid.     As  the  alcohol 

contracts  by  exposure  to  cold,  the  enamel  follows  it  towards 


46 


Pyrometers  of  Wedgwood  and  Daniell. 


the  bulb ;  but  when  it  expands,  the  enamel  remains  stationary, 
and  steers  the  liquid  to  pass  by  it.  When  the  mercury  con- 
tracts, the'enamel  does  not  follow  it;  but  when  the  mercury 
expands,  it  is  forced  along.  Consequently,  it  remains  at  the 
highest  temperature.  The -enamel,  in  the  tube  of  alcohol, 
will  indicate  the  lowest,  and  that  in  the  tube  of  mercury  the 
highest,  temperature  during  any  given  time. 

For  measuring  temperatures  below  39°  F.,  the  freezing 
point  of  mercury,  alcohol,  or  ether,  must  be  employed ;  for 
temperatures  above  662°,  no  liquid  can  be  used,  as  they  are 
all  either  decomposed,  or  dissipated  in  vapors.  For  very  high 
temperatures,  therefore,  some  of  the  more  infusible  solids 
are  used.  The  instruments  for  this  purpose  are  called 

Pyrometers.  This  term  is  derived  from  two  Greek  words, 
signifying  measurer  of  fire. 

1.  Pyrometer  of  Wedgwood.     This  is   founded    on  the 
property  which  clay  possesses  of  contracting  when  strongly 
heated,  without  expanding  when  cooled ;  but  the  indications 
of  this  instrument  cannot  be  relied  on,  and  it  is  seldom  used. 

2.  Pyrometer  of  Danidl.    This  instrument,  the  best  now 
in  use,  consists  of  a  bar  of  platinum  enclosed   in  a  case  7J 
inches  in  depth,  made  of  black  lead  :  one  end  of  the  bar  is 
fixed ;  the  other  is  made  to  move  an  index,  as  it  is  heated. 
This,  however,  is  not  perfectly  accurate,  owing  to  the  greater 
expansion  of  the  platinum,  in  high  temperatures,  with  equal 
degrees  of  heat.     Generally,  these  instruments  depend  upon 
the  elongation  of  a  metallic  bar  by  heat ;  and  one  of  the  best 
for  illustration  is  described  on  page  37. 

3.  On  the  same  principle  is  the 
Metallic    Thermometer  of  Brequet, 
(Fig.  18,)  for  temperatures  between 
the  freezing  and   boiling  points  of 
water.     It  consists  of  a  slip  of  silver 
and  one  of  platinum,  united  face  to 
face  with  solder,  and  coiled  into  a 
spiral,  r/,  one   end   of  which,  c,  is 
fixed,  while  the  other  is  connected 
with  an  index,  e,  which  moves  over 
a   circular,   graduated   plate,  f,  f. 
This  index  is  found  to  move  over 
equal  spaces  with  equal  additions  of 
caloric;  and  so  sensible  is  it  to  slight 


Fig.  18. 


Insensible  Caloric.  47 

variations,  that  when  enclosed  in  a  large  receiver,  which 
was  rapidly  exhausted  by  an  air  pump,  it  indicated  a  reduc- 
tion of  temperature  from  66°  to  25°=:  41°,  while  a  sensible 
mercurial  thermometer  fell  only  36°. 

It  will  be  readily  seen  that  thermometers  do  not  give  us 
the  absolute,  but  only  the  relative  quantity  of  caloric  con- 
tained in  bodies.  The  true  zero,  or  that  point  where  abso- 
lutely no  caloric  exists,  is  unknown.  Some  have  conjectured 
that  it  is  1200°  or  1400°  below  the  freezing  point  of  water. 
But  it  is  mere  conjecture ;  nor  is  it  known,  on  the  other  hand, 
how  high  a  temperature  might  result  from  an  accumulation 
of  heat.  Neither  limit  is  known.  The  thermometers  and 
other  instruments  measure  only  a  few  degrees,  in  the  middle 
of  a  scale,  whose  extremities  are  indefinitely  extended. 

SECT.  2.     INSENSIBLE  CALORIC. 

Every  one  sees  that  a  quart  of  water  contains  double  the 
quantity  of  caloric  which  is  contained  in  a  pint  of  the  same 
liquid,  when  the  temperature  of  both  is  the  same.  This  is 
called  insensible  caloric,  because  ij  does  not  affect  the  ther- 
mometer. 

Specific  Caloric.  But  different  quantities  of  caloric  are 
required  to  raise  equal  weights  of  different  substances  to  the 
same  temperature ;  and,  conversely,  different  quantities  arg 
given  out  by  them  in  cooling  equally.  Suppose,  for  example, 
that,  on  adding  a  given  quantity  of  heat  to  a  pound  of  water 
at  50°,  the  temperature  will  become  60°,  —  the  addition  of  the 
same  quantity  to  a  pound  of  sperm  oil  at  50°,  will  raise  the 
temperature  to  70°,  while  a  pound  of  pcftvdered  glass  will  be 
raised  from  50°  to  100°  by  the  same  quantity  of  caloric. 
The  temperature  is  increased  10°,  20°,  and  50°,  in  these  dif- 
ferent substances;  i.  e.,  if  the  required  temperature  to  which 
they  shall  be  raised  be  given,  the  oil  will  require  but  half  as 
much  heat  as  the  water,  and  the  glass  only  one  fifth  as  much. 
Specific  heat  is  the  relative  quantity  of  caloric  requisite  to 
raise  the  temperature  of  substances  equally;  i.  e.,  taking 
water  for  a  standard  at  1,  the  specific  heat  of  sperm  oil  will 
be  -fo>  and  of  powdered  glass  T2^.* 

*  The  phrage  capacity  for  caloric  was  formerly  used,  and  was  in- 


48  Methods  of  determining  Specific  Heat. 

In  these  experiments,  a  portion  of  caloric  disappears. 
This  portion  has  been  called  latent  or  combined  caloric, 
in  reference  to  the  theory  mentioned  in  the  note  below 
The  phrase  insensible  heat  is  preferred,  as  not  involving  any 
theory. 

Methods  of  determining  Specific  Heat.  Various  methods 
have  been  employed  to  ascertain  the  specific  heat  of  sub- 
stances. The  most  convenient  method  is  to  mix  with  the 
substances,  all  being  at  the  same  temperature,  a  given  quantity 
of  some  liquid,  as  water,  at  some  other  given  temperature, 
and  observe  the  relative  effects.  Thus,  as  in  the  example 
given,  a  pound  of  water  at  80°  may  be  added  to  a  pound  of 
the  same  at  50°,  and  the  resulting  temperature  will  be  the 
mean,  65° ;  another  pound  of  water  at  80°  to  a  pound  of  oil 
at  50°,  and  the  resulting  temperature  will  be  70° ;  i.  e.,  the 
oil  will  gain  20°  while  the  water  loses  but  10°  ;  and  ajra'm,  ;i 
pound  of  water  at^80°  to  a  pound  of  glass  at  50°,  and  the 
temperature  of  the  mixture  will  be  75°,  the  glass  gaining  25° 
by  5°  loss  of  the  water.  Other  and  more  difficult  experi- 
ments are  necessary  to  ascertain  the  specific  heat  of  gases 
and  of  solid  bodies. 

Laws  of  Specific  Heat.  The  principal  laws  of  specific 
heat  are  the  following :  — 

1.  At  the  same  temperature,  and,  in  the  case  of  gases, 
with  the  same  pressure,  the  specific  heat  of  each  body  is 
constant. 

2.  The  higher  the  temperature,  and,  in  the  case  of  gasrs, 
the  less  the  pressure,  the  greater  the  specific  heat  of  the  same 
body. 

This  is  supposed  to  be  owing  to  expansion.  In  gases,  the 
specific  heat  varies  with  the  density  and  elasticity  ;  the  greater 
the  density,  the  less  the  specific  caloric ;  and  the  greater  the 
elasticity,  the  greater  the  specific  caloric. 

3.  A  change  of  form  is  accompanied  by  a  change  of  spe- 
cific cidoric.     The  specific  heat  of  a  body,  as  it  passes  from 
a  solid  to  a  liquid  state,  is  increased.     It  is  also  supposed  to 

tended  to  convey  the  idea,  that  a  portion  of  the  heat  enters  into  and  is 
combined  with  substances  in  a  latent  state  ;  but  this  is  hypothetical, 
and  the  phrase  specific  heat  is  preferred,  as  involving  merely  a  fact. 


Effects  of  Insensible  Caloric.  49 

be  increased  by  a  change  of  the  body  from  a  liquid  state  to 
that  of  a  gas  or  vapor. 

4.  As  each  substance  has  a  specific  heat  peculiar  to  itself, 
it  follows  that  a  change  of  constitution  is  accompanied  by  a 
change  of  specific  heat. 

5.  A  change  of  specific  heat  is  generally  accompanied  by 
a  change  of  temperature.     Thus  the  expansion   of  a  gas, 
which  increases  its  specific  heat,  diminishes  its  temperature. 

As  a  practical  inference  from  the  doctrine  of  specific  heat, 
it  may  be  remarked,  that  much  less  fuel  will  be  necessary  to 
heat  some  substances  than  others. 

Effects  of  Insensible  Caloric. 

These  are  liquefaction  and  vaporization.* 

I.  LIQUEFACTION.  All  bodies  exist  in  one  of  three  states, 
solid t  liquid,  or  gaseous,  and  their  forms  seem  to  depend,  as 
we  have  seen,  (page  39,)  upon  the  relative  forces  of  cohe- 
sion and  caloric.  Hence,  by  the  increase  and  diminution 
of  either  of  these  forces,  we  can  cause  the  body  to  assume 
either  of  these  states.  If  a  solid  be  sufficiently  heated,  it  will 
become  liquid,  and  then  gaseous.  So  general  is  this  fact, 
that  it  may  be  stated  as  a  law. 

1.  Point  of  Liquefaction.      The   temperature  at  which 
liquefaction  takes  place,  is  called  the  melting  point,  or  point 
offitfiont  as  that  at  which  liquids  solidify  is  termed  the  point 
of  congelation.     These  points  are  identical;  but  there  is  a 
very  great  difference  in  substances  as  to  the  degree  of  heat 
which  is  required  to  fuse  them.     Each  substance  has  a  fixed 
point  effusion  and  of  congelation. 

2.  Caloric  of  Fluidity.    If  a  pound  of  ice,  which  is  at 
32°,  be  melted   in  a  pound  of  water  at  172°,  the  temperature 
of  the  whole  will  not  be  at  the  mean  of  102°,  but  at  32°, 
showing  that  140°  have  been  taken  into  a  latent  state,  by  the 
liquefaction  of  the  ice.     Generally,  liquefaction   is  accom- 

*  Classed  as  effects  of  insensible  caloric,  because  the  free  caloric 
passes  into  an  insensible  state,  which  is  essential  to  the  process. 

5 


50  Caloric.  —  Freezing  Mixtures. 

panied  by  the  conversion  of  free  into  insensible  heat.  The 
heat  which  thus  disappears  seems  essential  to  the  process  of 
liquefaction,  and  is  called  the  caloric  of  fluidity.  Its  quantity 
varies  in  different  substances,  as  in  the  following  table :  — 

Ice    .    .    ,  140°       Fahr.  Beeswax  .  175°    Fahr. 

Sulphur     .  143.68°     "  Zinc     .  .  490° 

Spermaceti  145°          "  Tin       .  .  500° 

Lead     .     .  162°         "  Bismuth  .  550° 

It  fine. 

When  the  process  is  reversed,  in  congelation,  this  insensi- 
ble caloric  is  thrown  out. in  a  free  state.  Thus  the  freezing 
of  water  produces  heat. 

3.  Freezing  Mixtures.  Liquefaction  may  be  produced 
without  the  addition  of  heat,  and  hence  the  caloric  of  fluidity 
will  be  obtained,  in  part,  from  the  temperature  of  the  sub- 
stances melted,  but  chiefly  from  the  surrounding  bodies ;  ;i 
great  degree  of  cold  is  thus  often  produced.  On  this  princi- 
ple varioys  freezing  mixtures  are  contrived.  The  most  com- 
mon method  of  producing  cold  is,  to  mix  together  eqiuil 
quantities  of  fine  salt  and  fresh  fallen  snow,  or  pounded  ice. 
The  salt  melts  the  snow  by  its  affinity  for  water,  and  the 
water  dissolves  the  salt,  so  that  both  are  liquefied.  The  drjrrer 
of  cold  produced  is  32°  below  the  freezing  point  of  water, 
or  at  zero.  This  led  Fahrenheit  to  commence  his  si -ilc  ;it 
that  point.  Any  other  substance,  which  has  a  strong  affinity 
for  water,  may  be  substituted  for  salt.  The  crystallized 
chloride  of  calcium  is  the  best,  because  it  produces  the  most 
rapid  liquefaction.  The  following  table,  constructed  by  Mr. 
Walker,  contains  the  proportions  of  several  substances  to 
produce  different  degrees  of  cold. 

Dep.  of  Cold 

produced. 


MIXTURES,              ftvPWei»htf           Thermometer  sinks 

Sea-salt    .    •;•'  ,     ,     ;     1  ) 

.     ,     .     to  —  5° 

Snow             .     .     .  •    ;•    2  J 

Sea-salt    2) 

Muriate  of  ammonia  .     1  > 

'<V^.    to  —  12° 

Snow        5  } 

Sea-salt    5  \ 

Nitrate  of  ammonia    .     5  > 

.     .     .     to  —  25° 

Snow        12  ) 

Diluted  sulphuric  acid     2  ) 
Snow       3  } 

from  +  32°  to  —  23° 

55deg. 


Freezing  Mixtures.  51 


Concentrated  muriatic  acid 


5  J  froM  +  330  to  _  2r    ^  deg 

Concentrated  nitrous  acid  4  »  from  4.  33°  to  _  30°    62 

Snow        ......  7  ) 

Chloride  of  calcium    .     .  5)  from  +  32o  to_40»    72 

Snow        ......  4  J 


Snow  P°taSSa    '  *om+32°to--5l0    83 

Freezing  may  also  be  effected  by  the  rapid  solution  of 
salts.  The  following  table  exhibits  the  proportions,  taken 
from  Walker's  essay  in  the  Phil.  Trans.  1795.  The  salts 
must  be  finely  powdered  and  dry. 

MIXTUIKS.  Thermometer*,* 


Muriate  of  ammonia  ..51 

Nitrate  of  potassa       .     .  5  >  from  +50°  to  +  10°    40  deg. 

Water      ......  16  ) 

Watef  ^  amm°nia  1  I  fr°m  +  5°°  l°  +  4°    4G 

Nitrate  of  ammonia    .     .  1  | 

Carbonate  of  soda      .     .  1  >  from  -f-  50°  to  —  7°    57 

Water      ......  l) 


Sulphate  of  soda         .     .         Urom  +  50°  to  --  3°  .53 

Diluted  nitrous  acid    .     .     2  ) 

Sulphate  of  soda     .     .     .     6| 

Nitrate  of  ammonia     .     .     5  >  from  -|-  50°  to  —  14°    64 

Diluted  nitrous  ncid     .     .     4  ) 

Rhosphate  of  soda       .     .     »  |  from  +  50o  to_j2o    02 

Diluted  nitrous  acid  .     4  J 

Phosphate  of  soda       .     .     9  | 

Nitrate,  of  ammonia     .  6  >  from  -f-  50°  to  —  21°    71 

Diluted  nitrous  acid     .     .     4  J 

Sulphate  of  soda  8  )  c 

Mariaticacid     ....     6}from  +  50   to        °     50 

Sulphate  of  soda  .     5  I  f  Q0  y 

Diluted  sulphuric  acid     .     4  ^ 

In  order  to  the  greatest  effect,  the  substances  should  be 
cooled  in  a  freezing  mixture  before  they  are  united. 

4.  The  degree  of  cold  produced  by  these  artificial  pro- 
cesses, is  limited.  The  greater  the  difference  between  the 
temperature  of  the  air  and  that  of  the  mixture,  the  more 
rapidly  will  the  air  communicate  caloric  to  it;  and  this  soon 


52  Vaporization  —  Ebullition. 

puts  a  limit  to  the  degree  of  cold.  According  to  Mr.  Walker, 
the  greatest  cold  did  not  exceed  100°  below  the  zero  of 
Fahrenheit.  But  a  more  intense  cold  is  produced  by  evapo- 
ration. 

5.  No  process,  however,  will  deprive  a  body  of  all  its 
caloric.  Dr.  Irvine  has  attempted  to  infer  the  absolute 
amount  from  the  specific  caloric  of  bodies ;  thus  ice  contains 
T\j  Jess  specific  caloric  than  water;  and,  as  this  T\y  is  equal  to 
140°,  it  is  inferred,  that  water  contains  ten  times  the  amount, 
or  1400°  of  caloric ;  but  the  estimates  made  by  different 
chemists  vary  from  900°  to  8000°,  which  shows  that  but  little 
confidence  can  be  put  in  their  calculations. 

II.  VAPORIZATION.  By  vaporization  is  meant  the  conver- 
sion of  liquid  and  solid  substances  into  vapor.  It  is  generally 
supposed  that,  if  sufficient  caloric  be  applied,  all  substances 
are  susceptible  of  this  change. 

A  gas  differs  from  a  vapor  in  the  circumstance  that  it  is 
not  so  easily  condensed  into  a  liquid ;  it  retains  its  state  at 
ordinary  temperatures  and  pressures.  "  The  only  difference 
between  gases  and  vapors  is  the  relative  forces  with  which 
they  resist  condensation." — T. 

Some  substances  yield  vapor  readily,  and  are  called  vola- 
tile. Others  sustain  the  strongest  heat  of  furnaces,  without 
volatilizing,  and  are  hence  said  to  bejixed  in  the  fire.  This 
difference  seems  to  depend  on  the  relative  forces  of  cohesion 
and  caloric.  Liquids  are  more  easily  vaporized  than  solids; 
and  solids,  with  a  few  exceptions,  like  camphor,  assume  the 
liquid  state  before  they  are  converted  into  vapor. 

Liquids  may  be  vaporized  in  two  ways:  1.  by  ebullition ; 
2.  by  evaporatibn.  In  the  first  case,  there  is  a  rapid  produc- 
tion of  vapor,  causing  commotion  in  the  liquid;  and  in  the 
second,  the  process  is  conducted  silently,  the  vapor  impercep- 
tibly passing  off  from  the  surface  of  the  liquid. 

Ebullition. 

1.  Boiling  Point.  The  temperature  at  which  a  liquid  is 
converted  by  ebullition  into  a  vapor,  is  called  its  boiling 
point.  This  point  varies  greatly  in  different  liquids  under  the 
same  circumstances,  and  in  the  same  liquid  under  different 


Ebullition.  53 

degrees  of  pressure.  But  each  liquid  has  a  fixed  boiling  point, 
when  all  the  circumstances  are  the  same. 

2.  The  chief  circumstance  which  modifies  theJooiling 
point  of  the  same  liquid,  is  the  pressure  of  the  atmosphere. 
A  column  of  air,  extending  to  the  top  of  the  atmosphere, 
presses  upon  every  square  inch  of  surface  with  a  force  equal 
to  151bs.  This  is  sufficient  to  sustain  a  column  of  mercury 
39  inches,  or  a  column  of  water  34  feet.  But  the  pressure 
varies  at  different  times  on  the  surface  of  the  earth ;  and  as 
we  ascend  high  mountains,  the  pressure  diminishes  rapidly. 
The  instrument  by  which  this  variation  is  measured  is  called 
the 

Barometer,  the  principle  of  which  may  be  illustrated  by 
filling  a  glass  tube,  open  at  one  end,  and  about  33  inches  long, 
wfth  mercury,  and  inverting  the  open  end  in  a  cup  of  the 
same  liquid.  (See  Fig.  19.)  The  pressure  of  the  atmos- 
phere on  the  surface  will  sustain  the  mercury  in  the  tube  to 
the  height  of  from  27  to  31  inches. 

When  the  barometer  stands  at  30  inches,  ether  boils  at 
96°,  alcohol  at  176°,  water  at  212°,  and  mercury  at  662°,  F. 
If  the  barometer  stand  at  28  inches,  all  these  substances  will 
boil  at  a  lower  temperature,  and  if  it  rise  to  31  inches,  the 
boiling  points  will  be  raised.  Hence  the  two  following  laws  : 

1 .  As  the  pressure  on  the  surface  of  liquids  diminishes , 
their  boiling  temperatures  diminish.  Thus  water  heated  to 
72°,  and  placed  under  the  receiver  of  an  air  pump,  will  boil, 
on  exhausting  the  air,  if  the  temperature  be  preserved. 

Ether  will  boil  violently,  under  an  exhausted  re-  Fig.  19. 
ceiver,  at  the  common  temperature  of  the   atmos- 
phere. 

Exp.  1.  Fill  the  barometer  tube  a  with  mercury,  (Fig.  19,) 
and  invert  it  in  a  cup  c  of  the  same  liquid ;  then  introduce  a. 
small  quantity  of  ether.  As  soon  as  it  reaches  the  vacuum 
r,  it  boils  rapidly,  and  the  vapor  forces  the  mercury  down  the 
tube. 

Fig.  20. 

Exp.  2.  The  pulse  glass  (Fig.  20) 
acts  on  the  same  principle.  It  is  con- 
structed by  blowing  a  bulb  b  on  the  end 
of  a  glass  tube,  in  which  a  small  open- 
ing is  made,  and  through  this  a  similar 


54L        Influence  of  Pressure,  upon  the  Boiling  Point. 

buH^  a  is  blown  on  the  other  end.  Some  spirits  of  wine  are  now  in- 
troduced,  and  heated  in  the  closed  bulb  a  until  the  vapor  escapes  from 
the  aperture  in  6,  when  it  is  hermetically  sealed.  The  heat  of  the  hand 
upon  e»er  bulb  is  sufficient  to  cause  violent  ebullition. 

Etheflboils  in  vacuo  at  —  44°,  alcohol  at  36°,  and. water 
at  72°,  an(}  liquids  generally  boil  at  temperatures  140°  less  in 
vacuo  thar^at  the  common  pressure. 

It  is  owing  to  this  fact,  that  intense  cold  can  be  produced 
by  boiling  ether  in  vacuo.  Water,  and  even  mercury,  under 
favorable  circumstances,  may  be  frozen.  To  render  the 
experiment  successful,  there  should  be  sulphuric  aci3  in 
the  receiver  to  absorb  the  vapor  of  ether,  which,  by  its 
pressure,  would  otherwise  soon  prevent  the  ether  from 
boiling. 

2.  As  the  pressure  on  the  surface  of  liquids  increases,  their 
boiling  temperatures  increase.  When  water  is  heated  to  the 
temperature  of  212°,  its  force  upon  each  square  inch  is  equal 
to  15  Ibs.  As  this  is  equal  to  the  pressure  of  the  atmosphere, 
it  will,  at  this  temperature,  escape  in  vapor;  hence  it  cannot 
be  heated  in  the  open  air  above  this  point.  But  if  the  pres- 
sure be  increased  sufficiently,  it  may  be  heated  to  any  extent, 

without  exhibiting  the  phenomena  of  ebullition. 

Fig.  21. 

Exp.  Boil  water  in  a  Florence  flask,  (Fig.  21,)  and  cork 
it  tight ;  the  ebullition  will  instantly  cease,  because  the 
steam  formed  will  press  upon  its  surface ;  but  by  pouring  on 
cold  water,  and  condensing  the  steam,  it  will  boil  violently; 
pour  on  warm  water,  ana  it  will  stop  boiling.  This  is  a 
convenient  mode  of  illustrating  both  of  the  above  laws :  as 
the  pressure  is  increased  by  the  formation  of  steam,  the 
boiling  point  is  raised,  while  it  is  lowered  by  condensing 
the  vapor  and  diminishing  the  pressure.  This  is  called  the 
culinary  paradox. 

But,  in  order  to  exhibit  the  influence  of  pressure  upon  the 
boiling  point,  we  must  employ  a  strong  metallic  boiler,  called 
a  digester,  which  consists  simply  of  a  strong  boiler  furnished 
with  stop-cocks  and  valves,  and  an  apparatus  to  ascertain  the 
temperature  and  pressure.  Water  confined  in  this  boiler 
may  be  heated  to  a  very  high  temperature  without  boiling ; 
but  the  steam  which  will  be  formed  will  endanger  the  boiler, 
before  we  can  ascertain  its  greatest  expansive  force  or  pres- 
sure upon  the  liquid. 


Marcet's  Digester. 


55 


For  experiments   on  the  pressure  of  Fig.  33. 

steam,  Marcet's  digester  (Fig.  22)  is 
well  adapted :  a  is  a  strong  brass  globe, 
into  which  a  portion  of  mercury  is  poured, 
and  then  half  filled  with  water;  6  a  ba- 
rometer tube  passing  through  a  steam- 
tight  collar  to  the  bottom  of  the  globe ;  c 
is  a  thermometer  graduated  to  400°  or 
500°  ;  d  a  stop-cock  ;  e  a  spirit  lamp  ;  * 
andy  a  brass  stand,  upon  which  the  whole 
is  supported.  Upon  the  stop-cock  d  a 
j^team  gun  may  be  screwed.  When  heat 
is  applied,  the  pressure  is  measured  by  ( 
the  height  to'  which  the  mercury  rises  in 
the  tube  6,  and  the  temperature  is  ascer- 
tained at  the  same  time  by  the  thermome- 
ter c.  On  the  application  of  heat,  as 
soon  as  the  water  boils,  the  thermometer 
will  stand  at  212°,  and  the  pressure,  of 
course,  will  be  equal  to  one  atmosphere, 
or  15  Ibs.  to  the  square  inch.  As  the 
temperature  increases  to  217°,  the  pres- 
sure will  elevate  the  mercury  5  inches, 
and  at  242°  about  30  inches,  each  degree  of  temperature 
raising  the  mercury  about  one  inch. 

Absorption  of  Free  Caloric  in  Ebullition.  When  water  is 
converted  into  steam,  a  great  quantity  of  sensible  heat  is 
taken  up  into  a  latent  state ;  which,  on  condensation,  again 
appears  in  a  free  state. 

If,  for  example,  steam  at  212°  sufficient  to  form  one  pint 


*  The  spirit  lamp  is  very  useful  for  pro- 
ducing heat  in  the  laboratory.  It  consists 
of  a  small  glass  lamp  a,  (Fig.  23,)  the  wick 
of  which  passes  through  a  metallic  collar  c; 
b  is  an  extinguisher,  to  prevent  the  wick 
from  absorbing  water  when  not  in  use.  It  is 
filled  with  alcohol,  which  burns  in  the  same 
manner  as  oil,  but  does  not  yield  any  smoke. 
A  common  glass  or  tin  lamp  will  answer  a 
very  good,  purpose,  using  alcohol  instead 
of  oil. 


Fig.  33. 


a 


56  Steam. 

of  water,  be  condensed  in  ten  pints  of  water  at  117°,  the 
temperature  of  the  whole  will  be  212°;  the  ten  pints  will  be 
elevated  95°  :  this  is  equivalent  to  raising  the  temperature  of 
one  pint  950°.  The  latent  heat  of  steam  is,  therefore,  950°  ; 
other  substances  are  subject  to  the  same  law.  Hence  it  may 
be  stated  generally,  that,  in  ebullition,  he.at  is  taken  into  a 
latent  state,  and  given  out  on  condensation. 

The  latent  heat  of  different  vapors  is  various,  as  may  be 
seen  in  the  following  table:  — 

Latent  Heat. 

Vapor  of  water  at  its  boiling  point    .     .  .  967° 

Alcohol     V  .    ;.     .:  \    >  .  .  442 

Ether 302.379 

Petroleum        .     .     .''  .   '.     .  .  177.87 

Oil  of  turpentine      .     ;:'' V    .  .  177.87 

Nitric  acid      .".     j    .•;!".  .  531.99 

Liquid  ammonia        .    .     .     .  .  837.28 

Vinegar  '-.  '.;"..''.•.     »  .  875 

Steam  is  formed,  ordinarily,  by  ebullition.  At  the  moment 
when  water  takes  the  state  of  vapor,  in  the  open  air,  it  has  an 
expansive  force  equal  to  one  atmosphere,  or  15  Ibs.  on  the 
sq.  inch.  If,  then,  it  be  disconnected  from  water,  its  laws  of 
expansion  a«d  contraction,  at  all  temperatures  above  212°, 
•are  the  same  as  all  gaseous  bodies.  Equal  increments  of 
caloric  expand  it  equally,  and  its  expansion  is  in  the  ratio  of 
the  heating  power;  for  every  degree  of  Fahrenheit's  ther- 
mometer, it  expands  ^fa  of  what  its  volume  would  be  at  32°, 
if  it  did  not  condense.  It  may  be  heated,  like  any  gas,  until 
it  is  red  hot,  if  the  vessel  is  sufficiently  strong.  But  steam 
is  usually  formed  in  the  boiler  where  water  is  present,  and,  as 
the  temperature  increases,  fresh  portions  of  steam  are  con- 
stantly added  to  that  which  is  already  formed,  so  that  its 
expansive  force  increases  in  a  much  more  rapid  ratio. 

According  to  the  experiments  of  Dulong  and  Arago,  if  we 
take  atmospheric  pressure  for  unity,  we  shall  find  the  pres- 
sure of  steam  at  233.96°,  equal  to  1  j  atmospheres. 

250.52  equal  to  2  atmospheres,  or  301bs.  to  the  sq.  inch. 

275.18      "         3  "  45 

320.36      "         6  "  90        " 


Uses  of  Steam.  57 

374      equal  to  12  atmospheres,  or  1801bs.  to  the  sq.  inch. 
435.56      "       24  "  360       "  " 

486.59  "      40  "  600 

510.60  "       50  "  750       " 

When  steam,  at  a  high  temperature,  is  condensed  in  cold 
water,  a  loud,  crackling  noise  is  heard,  which  is  due  to  the 
collapse  of  the  water,  a  vacuum  being  formed  by  the  sudden 
condensation  of  the  steam. 

Ezp.  Let  a  jet  of  steam  rush  from  the  digester  through  a  pipe  into 
cold  water. 

When  liquids  are  converted  into  vapor,  under  high  pres- 
sure, the  vapor  is  very  dense.  If,  then,  it  is  allowed  to  escape 
from  the  orifice  of  the  boiler,  the  hand  may  be  held  at  a  short 
distance  without  being  burned,  though  the  temperature  of  the 
steam,  before  it  escapes,  is  several  hundred  degrees. 

This  is  due  to  its  expansion,  and  the  consequent  absorption 
of  its  sensible  caloric.  When  water  is  converted  into  steam 
at  212°,  it  absorbs  950°  of  caloric.  If  now  it  be  condensed 
to  32°,  it  will  give  out  950°  of  latent,  and  180°  of  sensible 
caloric^  1130°.  Now,  if  we  take  the  same  weight  of  steam, 
at  a  higher  temperature,  250°,  and  condense  it  to  32°,  it  will 
give  out  912°  of  insensible,  and  218°  of  sensible  caloric  = 
1130°;  hence  the  sum  of  the  sensible  and  insensible  caloric 
contained  in  equal  tonights  of  steam,  is  exactly  the  same  at  all 
temperatures  =.  1 130°. 

The  absorption  of  caloric  seems  to  perform  a  similar  office 
in  vaporization  and  liquefaction,  being  essential  both  to  the 
formation  of  vapors  and  of  liquids. 

Application  of  Steam  to  practical  Purposes. 

1.  It  is  used  for  warming-  rooms.  For  this  purpose  it  is 
conveyed  in  pipes,  and  continues  to  heat  the  room  until  its 
caloric  is  nearly  exhausted.  It  is  then  condensed  to  water, 
and  gives  out  its  latent  caloric. 

Every  cubic  foot  of  steam  in  the  boiler  will  heat  200 
feet  of  space  to  70°  or  80° ;  and  each  square  foot  of  steam 
pipe  will  warm  200  cubic  feet  of  space. 

It  is  used   for  heating   water-baths   and  dyeing-vats;  for 


58  Caloric.  —  Steam  Engine. 

bleaching  cloth;  for  producing  a  vacuum  by  its  condensa- 
tion; for  various  culinary  purposes;  also,  for  .drying  various 
substances,  such  as  muslins,  calicoes,  gun-powder,  etc. 

2.  But  its  most  important  application  i?  to  the  propelling 
of  machinery  :  the  instrument  employed  for  this  purpose  is  the 
steam  cngint;  the  invention  ef  which  is  due  to  Capt.  Savery. 

The  principle  of  his  invention  may  be  illus- 
trated by  a  tube,  with  a  bill  blown  at  one  end, 
(Fig.  24):  fill  this  with  water,  and  invert  it  in 
the  same  liquid  ;  apply  heat  to  the  bulb,  and, 
as  soon  as  the  water  is  at  212°,  steam  will  be 
formed,  and  force  the  water  out ;  but,  as  soon  as 
the  steam  comes  in  contact  with  the  cold  water 
in  the  vessel,  it  is  suddenly  condensed;  a 
vacuum  is  formed,  and  the  atmosphere  forces 
the  water  with  great  violence  up  the  tube,  so 
as  to  fill  the  bulb.  If  a  piston  be  fitted  to 
the  tube,  it  will  constitute  the  instrument  devised  by  Dr. 
Wollaston,  except  that  the  steam  in  his  apparatus  is  con- 
densed by  putting  the  bulb  into  cold  water.  The  atmos- 
phere presses  the  piston  down,  while  it  is  raised  by  causing 
the  water  in  the  bulb  to  boil. 

The  moving  power  of  the  steam  engine  is  the  same  as  in 
this  apparatus,  but  the  steam  is  condensed  in  a  separate  ves- 
sel called  the  condenser :  this  constitutes  the  improvement  of 
Watt,  by  which  means,  the  temperature  of  the  cylinder  is 
never  below  212°  Fahr. 

3.  The  steam  generator  of  Mr.  Perkins  sustains  a  pres- 
sure  of  800,  1000,  and  even  15001bs.  on  the  square  inch. 
The  steam  is  then  so  hot  as  to  set  fire  to  tow,  and  even  ignite 
the  generator  at  its  orifice.     At  this  very  high  temperature, 
it  is  about  half  as  heavy  as  water.     It  is  a  remarkable  fact, 
that,  at  such  pressures,  the  steam  will  not  rush  through  a 
small  aperture,  through  which  it  will  rush  with  great  violence, 
and  a  roaring  noise,  when  the  temperature  arid  pressure  are 
diminished.     Mr.  Perkins  thinks  that   400    atmospheres,  or 
6000  Ibs.  to  the  square  inch,  is  the   maximum  of  pressure; 
i.  e.,  that  under  this  pressure,  water  will  remain  liquid  at  any 
temperature,  even  at  a  white  heat.     The  boiler  of  the  gener- 
ator is  small,  and  not  more  than  a  gallon  of  water  is  used  at 
a  time. 


Evaporation.  59 

Steam  Artillery.  Mr.  Perkins  has  succeeded  in  applying  this  amaz- 
ing force  to  the  propelling  of  cannon  balls.  He  states  that  sixty  41b. 
balls  can  be  discharged  in  a  minute,  with  the  accuracy  of  a  rifle 
musket,  and  to  a  proportional  distance.  A  musket  may  also  be  made 
to  throw  from  one  hundred  to  a  thousand  balls  per  minute.  It  is  great- 
ly to  be  hoped  that  his  experiments  will  prove  successful ;  for,  if  such 
engines  of  death  could  be  brought  into  the  field  of  battle,  few  nations 
would  be  willing  to  settle  their  disputes  in  that  way.  Few  would  fight 
in  the  prospect  of  certain  death. 

Fig.  25. 

Distillation.  This  process  is 
conducted  by  converting  liquids 
into  vapor,  which  passes  into  a 
long,  metallic  tube,  or  worm,sur 
rounded  by  cold  water.  The  va- 
por is  condensed,  and  the  liquor 
runs  off  at  the  opposite  extremity 
of  the  tube.  Fig.  25  represents 
this  apparatus ;  a  a  copper  boiler, 
6  its  head,  connected  with  the 
worm,  which  is  coiled  in  the  refrigerator  d.  The  vessel  d  is 
filled  with  cold  water  to  condense  the  vapor  in  the  worm  as 
it  passes  through  it. 

Evaporation. 

The  only  difference  between  evaporation  and  ebullition  is, 
that  the  one  takes  place  quietly,  and  the  other  with  the  ap- 
pearance of  boiling.  Evaporation  takes  place  at  all  temper- 
atures, but  ebullition  at  fixed  temperatures.  The  former 
takes  place,  not  only  in  all  liquids,  but  in  many  solids,  as 
camphor;  the  latter  is  confined  to  liquids. 

1.  Evaporation  is  much  more  rapid  in  some  liquids  than  in 
others,  and  it  is  always  found  that  those  liquids  whose  boiling 
points  are  lowest  evaporate  with  the  greatest  rapidity. 

Thus  alcohol,  which  boils  nt  a  lower  temperature  than 
water,  evaporates  also  more  freely,  arid  ether,  whose  point 
of  ebullition  is  yet  lower  than  that  of  alcohol,  evaporates 
with  still  greater  rapidity.  Also,  if  the  temperature  of  the 
liquid  be  raised  or  lowered,  the  evaporation  will  be  more  or 
less  rapid. 

2.  Increase  of  pressure  checks  evaporation,  and  diminution 
of  pressure  promotes  it ;  thus  water  will  evaporate  much  more 
rapidly  in  a  vacuum. 


60  Caloric.  —  Uses  of  Evaporation. 

This  is  precisely  what  we  should  expect  from  the  fact 
just  mentioned,  that  evaporation  is  most  rapid  in  liquids 
whose  boiling  point  is  lowest;  for  the  diminution  of  pressure 
lowers  the  boiling  point.  From  the  three  facts  which  have 
been  mentioned,  it  may  be  inferred  that  evaporation  is  more 
rapid  as  the  distance  between  the  boiling  point  and  the  tttn- 
perature  of  the  substance  diminishes. 

The  other  circumstances  that  influence  the  process  of 
evaporation  are, 

3.  Extent  of  Surface.     As  evaporation  goes  on  from  the 
surface,  it  is  evident  that,  the  greater  the  extent  of  surface, 
the  more  rapid  the  evaporation.' 

4.  State  of  the  Atmosphere.     If  the  atmosphere  be  already 
saturated  with  moisture,  evaporation  will  be  checked ;  or,  if 
the  air  remain  still,  it  will  soon  become  saturated,  and  the 
evaporation  is  promoted  by  the  motion  of  the  air. 

5.  Absorption  of  Free  Caloric  by  Evaporation.     If  a  dish 
of  water  be  placed  in  the  exhausted  receiver  of  an  air  pum]>, 
and  another,  of  sulphuric  acid,  to  absorb  the  vapor  of  the 
water,  the  water  will  evaporate  so  rapidly,  as  to  be  frozen  by 
the  absorption  of  its  sensible  caloric.*     Hence  the  cffcit  of 
evaporation  is  to  produce  cold ;  because  the  sensible  caloric 
passes  into  an  insensible  state. 

Exp.  This  may  be  further  illustrated  by  filling  a  small  glass  tube 
with  water,  and  surrounding  it  with  cotton  wool.  If  the  cotton  wool 
be  soaked  with  ether,  and  a  current  of  air,  from  a  common  Iwlluws,  In- 
directed  upon  it,  the  water,  in  the  course  of  a  few  moments,  will  congeal. 

Exp.   A  very  satisfactory  experiment 
is  performed  with  the  cryophorus,  an  in-        .  Fig.  26. 

strument  invented  by    Dr.    Wollaston.          * -  - -    - 

It  consists  of  two  glass  balls,  (Fig.  20,)     %/^\^  ~?\ 

connected  by  a  glass  tube.     Both  balls     \N=^ 

are  free  from  air  ;  but  one  of  them  con-      jF^ 

tains  a  portion  of  distilled  water.    When 

the  other  ball  is  placed  in   a  freezing  mixture,  so  as^  to  condense  the 

watery  vapor  as  fast  as  it  formed,  the  evaporation  is  so  rapid  from  the 

*  The  most  intense  cold  which  has  been  produced  is  the  effect  ot 
evaporation.  If  a  large  quantity  of  carbonic  acid  gas  be  condensed 
into  a  liquid  by  pressure,  and  suffered  to  escape  through  a  small  aper- 
ture, it  will  congeal  by  its  own  expansion  ;  the  solid  acid  thus  formed 
will  evaporate  so  rapidly  in  a  vacuum,  as  to  produce  the  cold  of —  13(>° 
Fahr.  At  this  temperature,  the  strongest  alcohol  becomes  viscid,  and 
common  alcohol  becomes  frozen. 


Uses  of  Evaporation.  61 

surface  of  the  water  in  the  other  ball,  as  to  freeze  it  in  two  or  three 
minutes. 

6.  Cause  of  Evaporation.     The  cause  of  evaporation  is, 
doubtless,  the  same  as  that  of  ebullition  —  caloric;  although 
some  have  attempted  to  account  for  it  on  the  supposition  of 
an  affinity  between  the  air  and  the  evaporated  liquid  ;  but 
evaporation  in  a  vacuum  is  fatal  to  this  hypothesis. 

7.  Uses  of  Evaporation.     It    is  well   fitted   for   cooling 
apartments.     All  that   is  necessary    for  this   purpose,  is  to 
sprinkle  the  floor  with  water. 

It  moderates  the  he;it  of  warm  climates;  hence  places  near 
large  bodies  of  water  are  cooler  in  the  summer  than  those 
more  remote,  and  the  greater  the  heat  from  the  sun's  rays, 
the  more  rapid  the  evaporation,  and  of  course  the  greater 
quantity  of  sensible  caloric  goes  into  an  insensible  state. 

Evaporation  not  only  takes  place  from  the  surface  of  water, 
but  from  the  surface  of  the  earth,  and  from  plants  and  ani- 
mals: hence  it  tends  to  defend  the  animal,  as  well  as  the 
vegetable  system,  from  external  heat.  When  an  animal  is 
exposed  to  external  heat,  perspiration  commences  over  the 
whole  surface,  and  the  liquid,  in  passing  to  a  vapor,  absorbs 
the  sensible  caloric.  On  this  principle  firo-kings  subject 
themselves  to  a  high  temperature,  with  but  little  inconve- 
nience. The  oven  girls  of  Germany,  also,  often  expose  them- 
selves to  a  temperature  of  from  250°  to  280°,  and  one  girl 
breathed  five  minutes  in  an  atmosphere  of  325°.  In  these 
cases,  water  boils  rapidly,  and  beef-steak  is  cooked  in  a 
few  minutes.  If,  however,  the  air  be  moist,  or  the  body  be 
varnished,  so  as  to  prevent  perspiration,  the  heat  cannot  be 
sustained  for  a  moment.  The  heat  produced  by  violent 
exercise  is  carried  off  in  the  same  manner. 

But  the  vital  principle,  doubtless,  has  much  to  do  in  forti- 
fying the  system  against  the  extremes  of  heat  and  cold ;  for, 
although  men  may  be  subjected  to  a  range  of  temperature 
of  more  than  400°,— from  350°  above  to  75°  or  80°  below 
zero, — -the  temperature  of  their  bodies  does  not  vary  five 
6 


62  Caloric.  —  Hygrometers. 

degrees,  but  remains  stationary  at  98°  and   100°,  during  a/I 
the  varieties  of  external  temperature. 

Evaporation  often  fills  the  air  with  deadly  miasma.  The 
fever  and  ague  is  supposed  to  be  produced  in  this  way.  Con- 
siderable effect  is  also  produced  upon  the  bulk  of  gases,  and 
it  becomes  a  point  of  great  interest  to  ascertain  the  amount, 
especially  when  delicate  experiments  are  to  be  performed. 

The  atmosphere,  of  course,  always  contains  a  portion  of 
watery  vapor.  At  the  freezing  point  it  contains  f\^  of  its 
volume,  and  the  higher  the  temperature,  the  more  vapor  is 
it  capable  of  sustaining.  The  instruments  for  measuring  the 
amount  of  vapor  in  the  air,  and  other  gases,  are  called 

Hygrometers.  These  vary  in  form,  but  may  ail  be  reduced 
to  three  principles. 

1.  TMie  first  is  founded  on  the  property  of  some  substances 
to  elongate  when  placed  in  a  moist  atmosphere,  and  to  con- 
tract when  dry.     The  human  hair  possesses  this  property  in 
an  eminent  degree,  and  is  the  substance  employed  by  Saus- 
sure. 

2.  The  second  kind  of  hygrometer  depends  on  the  rapidity 
of  evaporation,  the  temperature  and  pressure  being  the  same; 
the  more  vapor  there  is  in  the  air,  the  slower  will  the  process 
go  forward.     Leslie's  hygrometer  is  constructed  on  this  prin- 
ciple. 

3.  The  third  kind  depends  on  the  fact  that,  if  a  cold  body 
be  introduced  into  moist  air,  the  moisture  will  condense  on 
it;  as  is  sometimes  seen  on  the  surface  of  glass  and  earthen 
vessels  filled  with  cold  water,  and   is  an   indication  of  rain. 
The   temperature    at  which   the   moisture    is  condensed  is 
called  the  dew  point. 

Application  of  the  Laws  of  Insensible  Caloric  to  the  Explana- 
tion of  Natural  Phenomena. 

1.  We  have  seen  that,  when  solids  are  converted  into  li- 
quids, they  absorb  large  quantities  of  caloric.  Hence  the 
process  of  thawing,  contrary  to  the  common  belief,  is  a 
freezing  process.  Ice,  in  becoming  water,  absorbs  140°  of 
sensible  caloric ;  hence  countries  surrounded  by  water  are 


Explanation  of  Natural  Phenomena.  63 

cooler  in  the  spring  than  those  where  less  ice  is  formed  dur- 
ing the  winter. 

2.  Liquids,  in  passing  to  vapors,  absorb  sensible  caloric. 
In  the  vaporization  of  water,  nearly  1000°  of  caloric  are  ab- 
sorbed.    It  is  therefore  a  much  more  powerful  cooling  pro- 
cess than  the  liquefaction  of  ice;  hence  the  heat  of  warm 
countries   is  greatly  reduced   by  the  constant   formation  of 
vapor.     This  is  the  reason  why  the  transition  from  the  cold 
of  winter  to  the  heat  of  summer  is  not  sudden,  but  gradual ; 
the  ice   and  the  water   cannot   obtain   caloric  in  sufficient 
quantities  to  convert  them  into  vapor. 

3.  When  vapors  and  gases  become  liquids,  they  give  out 
large  quantities  of  caloric;  hence  it  is  usually  warmer  after 
a  rain,  a  large  quantity  of  caloric  being  evolved  by  the  con- 
densation of  the  vapor  in  the  atmosphere.     If,  nowever,  the 
earth  is  dry  and  hot,  the  heat  converts  the  water  into  vapor, 
and  renders  the  air  cooler. 

4.  Liquids,  in  becoming  solids,  give  out  caloric;  hence 
the  process  of  freezing  is  a  heating  process.     To  prevent 
some  substances  from  freezing,  we  have  only  to  place  them 
near  those  which    congeal    at  a  higher  temperature;    thus 
water  placed  in  a  cellar  will  prevent  vegetables  from  freezing, 
because   they   require    a  lower  temperature  than   water  to 
freeze  them ;  before  they  reach  the  point  of  congelation,  the 
freezing  of  the  water  renders  its  insensible  caloric  sensible, 
and  prevents  them  from  attaining  it. 

By  the  process  of  converting  water  into  ice,  —  a  process 
constantly  going  forward  when  the  thermometer  stands  at 
32°  Fahr.,  —  large  quantities  of  caloric  are  thrown  off  into  the 
itmosphere ;  hence  the  shores  of  a  country  are  warmer  in 
the  winter  than  the  interior ;  hence,  too,  the  approach  of  the 
cold  season  is  gradual,  —  the  greatest  degree  of  cold  rarely 
occurs  till  after  the  winter  solstice,  twentieth  of  ^December. 
Were  these  laws  suspended,  September  and  March  would 
be  of  equal  temperatures.  June  would  be  the  warmest,  and 
December  the  coldest  month  in  the  year. 


64  Caloric.  —  Sources  of  Caloric. 


SECT.  3.     SOURCES  OF  CALORIC. 

The  principal  sources  of  caloric  are, 

1.  The  sun. 

2.  Chemical   action,  including  electricity,  galvanism,  and 
combustion. 

3.  Condensation  by  mechanical  action,  including  percus- 
sion and  friction."" 

4.  Vital  action. 

1.  Sun.    The  heat  produced  by  the  sun  varies  with  the 
kind  and  color  of  the  surface,  according  to  principles  already 
noticed.     The  temperature  produced  by  their  direct  action  is 
seldom  more^than  120° ;  but,  when  the  rays  are  concentrated 
by  means  of  convex  lenses,  or  concave  mirrors,  a  very  intense 
heat  is  produced.     Lenses  have  been  constructed  concen- 
trating sufficient  heat  to  melt  some  of  the  most  refractory 
metals ;  but  the  most  intense  heat,  at  any  considerable  dis- 
tance, is  produced  by  several  concave  mirrors,  which  reflect 
the  rays  to  one  focus.     Metals  and  minerals  have  thus  been 
melted  at  the  distance  of  40  feet,  and  wood  ignited  at  the 
distance  of  120  feet  from  the  mirrors. 

2.  Chemical  Action.     Caloric  is  often  produced  by  chem- 
ical and  electrical  action.     A  very  great  heat  occurs  in  the 
phenomena  of  combustion,  which  may  be  defined  to  be  the 
disengagement  of  light  and  heat  in  substances  by  chemical 
action.     But  the  most  intense  heat  is  produced  by  voltaic  or 
electrical  action. 

3.  Condensation.     It  has  been   already  stated   that  sub- 
stances develop  caloric  by  diminution  of  their  bulk,  as  when 
gases  pass  to  liquids  and  to  solids.     A  fire  is  often  kindled 
by  rubbing  pieces  of  dry  wood  against  each  other;  heavy 
machinery,  if  not  properly  oiled,  often    ignites  wood,   and 
axletrees  of  carriages  are  burned  off;  the  sides  of  vessels  are 
set  on  fire  by  the  descent  of  the  cable.     The  friction  in  these 
cases  condenses  the  parts,  and  the  caloric  is  developed.     So, 


Nature  of  Caloric.  65 

when  iron  is  struck  with  £  hammer  several  times,  it  becomes 
hot.  Fire  is  also  struck  from  steel  with  any  hard  substance, 
like  flint.  This  is  denominated  percussion. 

4.  Vital  Action.  The  caloric  developed  by  vital  action  is 
supposed  to  be  owing,  in  part,  to  the  chemical  action  of  the 
air  upon  the  blood ;  but  it  is  more  probable  that  the  vital 
principle  operates  to  produce  most  of  it,  in  a  way  not  well 
understood. 

Sources  of  Cold.  The  sources  of  cold  are,  liquefaction, 
vaporization,  and  rarefaction.* 

SECT.  4.    NATURE  OF  CALORIC. 

On  this  subject  there  are  two  theories.  Sir  H.  Davy  and 
some  others  considered  caloric  as  a  property  of  matter ;  and 
Sir  William  llerschel  and  Prof.  Airy  have  attempted  to  ex- 
plain its  nature  by  supposing  that  there  exists  a  subtile  ether, 
which  pervades  all  space  and  all  matter,  and  that  caloric  is 
the  effect  of  vibrations  made  in  this  fluid,  somewhat  similar 
to  the  vibrations  of  the  air  which  produce  the  sensation  of 
sound.  This  theory  is  called  the  undulatory  theory,  and  is 
most  favorably  received  by  chemists. 

Sir  Isaac  Newton  supposed  that  caloric  was  a  subtile,  ma- 
terial fluid.  If  caloric  is  material,  it  is  matter  under  very 
peculiar  circumstances.  So  far  as  we  can  determine,  it  pos- 
sesses few,  if  any,  of  the  common  properties  of  matter;  its 
particles  are  self-repellent,  opposed  to  cohesive  attraction. 
If  it  is  material,  its  particles  must  be  exceedingly  small,  as 
they  penetrate  all  other  substances,  however  dense.  They 
must  also  be  influenced  by  gravity ;  but  no  quantity  of  them, 
however  great,  possess  the  least  appreciable  weight.  It  pos- 
sesses neither  extension  nor  impenetrability ;  but  if  it  is  mat- 
ter, it  must  have  these  properties. 
6* 


66         Physical  Properties  of  Light  —  Refraction. 

CHAPTER    II. 

LIGHT. 

The  physical  properties  of  light  belong  to  the  science  of 
Optics,  a  branch  of  Natural  Philosophy.  But  light  has  also 
chemical  properties,  which  come  within  the  province  of 
Chemistry. 

I.  Physical  Properties  of  Light.     Light  is  emitted  from 
every  visible  point  of  a  luminous  object,  and  is  equally  dis- 
tributed on  all  sides,  if  not  interrupted,  diverging  like  radii 
drawn  from  the  centre  to  the  circumference  of  a  sphere.     It 
travels  at  the  rate  of  192,000  miles  in  a  second,  requiring 
about  eight  <minutes  to  pass  from  the  sun  to  our  earth.     Its 
velocity  is  so  great,  that  the  light  emitted  in  the  firing  of  a 
cannon,  or  a  sky-rocket,  will  be  seen  by  different  spectators 
at  the  same  instant,  whatever  may  be  their  respective  dis- 
tances   from  it ;    the   time  required  for  light  to  travel  one 
hundred  or  one  thousand  miles  being  inappreciable  by  our 
senses.     When  light  falls  upon  any  body,  it  is  either  reflected, 
refracted,  or  absorbed. 

II.  Reflection.     The  reflection  of  light  is  influenced  by 
the  same  circumstances  as  that  of  caloric,  and  follows  tho 
same  laws ;  the  angles  of  incidence  and  reflection  are  equal. 
(Fig.  6,  page  31.)     It  is  owing  to  the  reflection  of  light  that 
we  are  able  to  see  the  various  objects  in  nature,  an  image 
of  the  object  being  formed  by  the  reflected  rays  upon  the 
retina  of  the  eye. 

III.  Refraction.     When  a  ray  passes  from  a  rarer  to  a 
denser  medium,  as  from  air  into  water,  it  is  refracted  towards 
a  perpendicular  to  the  refracting  surface :  this  property  is 
called  refrangibility. 

Thus  (Fig.  27),  I  is  the  ray  before  it  reaches  the  refract- 
ing surface  3.  Instead  of  passing  directly  through  to  a,  it 
is  bent  towards  the  perpendicular,  to  the  surface  py  and  pro- 


Decomposition  of  Light. 


67 


ceeds  to  r.    But  in  passing  from  a  denser  Fig.  27. 

to  a  rarer  medium,  it  is  refracted  from    /  j         fi 
a  perpendicular   to  the   refracting  sur- 
face.    Thus,  in  passing  from  r,  it  is  re- 
fracted at  the  surface  towards  I,  instead 
of  proceeding  to  d.      Hence   a    stick 
partly  in  water  appears  bent.     Objects 
viewed  through  some  substances,  as  Ice- 
land spar,  appear   double  in  consequence  of  a  double  re- 
fraction. 

IV.  Decomposition  of  Light.  Solar  and  stellar  light  con- 
taiu  three  kinds  of  rays:  — 

1 .  Colorific,  or  rays  of  color. 

2.  Calorific,  or  rays  of  heat. 

3.  Chemical  rays,    or   those    which    produce    chemical 
effects. 

1.  Colorific  Rays.  These  may  be  separated  into  seven 
primary  colors  :  red,  orange,  Jellow,  green,  blue,  indigo,  and 
violet. 

Fig.  28. 
C 


The  instrument  by  which  this  separation  is  effected  is  a 
triangular  prism  (Fig.  28)  of  glass,  ice,  or  any  transparent 
substance.  A  beam  of  light  r  is  admitted  into  a  dark  room, 
and,  passing  obliquely  through  two  sides  of  the  prism  p,  is 
refracted  by  both.  The  different  colors  are  separated,  be- 
cause some  are  refracted  more  than  others  ;  and,  instead  of  a 
white  spot  after  the  beam  passes  through  the  prism,  as  at  8, 
there  appears  a  long,  colored  surface  c,  called  the  solar  spec- 
trum. 

Dr.  Wollaston  supposes  that  there  are  but  four  colors,  viz. : 
red,  green,  blue,  and  violet,  occupying  spaces  in  the  propor- 
tion of  16,  23,  36,  28. 


68  Calorific  Rays  —  Daguerreotype. 

According  to  Sir  D.  Brewster,  there  are  but  three  colorf, 
red,  yellow,  and  blue,  a  mixture  of  which  produces  the  others. 

The  prismatic  colors  differ  in  their^  illuminating  power. 
This  is  greatest  in  the  yellow  and  green,  and  diminishes  each 
way  to  the  violet  and  red. 

2.  Calorifa  Rays.     The  calorific  rays  exist  in  the  greatest 
intensity  in,  and  near  the  red  rays,  and   diminish  rapidly 
towards  the  violet ;  the  greatest  heat  is  sometimes  entirely 
without  the  red  rays;  this,  however,  depends  upon  the  kind 
of  substances  used  to  separate  the  rays ;  in  some  cases,  it  is 
quite  on  the  verge  of  the  orange.      The  refrangibility,  then, 
of  the  calorific  rays  is  much  less  than  that  of  the  colorific. 
This  is  shown  also  by  the  fact  that,  when  the  solar  rays  are 
concentrated  by  a  convex  lens,  the  focus  of  heat  is  farther 
from  the  lens  than  that  of  light. 

3.  Chemical  Rays.     On  the  side  of  the  spectrum,  a  little 
beyond  the  violet,  are  invisible  rays,  which  have  a  peculiar 
effect  upon  chemical  changes.     They  are  most  powerful  on 
the  verge  of  the  violet,  and  diminish  towards  the  red. 

1.  Photographic  drawing  depends  upon  the  influence  of 
these  rays. 

Exp.  Cover  one  side  of  a  plate  of  glass  with  beeswax,  colored  with 
lamp-black,  and  draw  a  picture  on  it  by  removing  the  wax  witli  a  sharp 
point.  If  then  a  solution  of  salt  in  water  be  spread  on  a  piece  of  white 
paper,  and  the  nitrate  of  silver  in  solution  poured  upon  it,  the  chloride 
of  silver  will  be  formed.  Place  the  paper  then  over  the  glass,  and  the 
sun's  rays  passing  through,  where  the  wax  is  removed,  will  form  a 
picture  upon  the  paper,  by  changing  the  chloride  black  wherever  they 
strike  it. 

Exp.  Soak  a  piece  of  white  paper  in  a  saturated  solution  of  bichromate 
of  potassa,  dry  it  rapidly,  and  put  it  in  a  dark  room.  Place  over  it 
prints,  dried  plants,  etc.,  and  expose  it  to  the  sun;  the  objects  will  be 
represented  yellow  on  an  orange  ground.  To  fix  the  drawing,  wash  it 
carefully,  to  dissolve  the  salt  which  has  not  been  acted  upon  by  the 
light.  The  object  will  then  appear  white  on  an  orange  ground. 

If  sulphate  of  indigo  be  used  with  the  bichromate  of 
potassa,  it  will  give  to  the  object  and  to  the  paper  different 
shades  of  green. 

2.  Daguerreotype.     A  method  of  fixing  the  images  of  ob- 
jects on  metal  has  lately  been  devised  by  Daguerre. 


Magnetic  Rays.  69 

£//?.  Expose  a  plate  of  silvered  copper,  well  cleaned  with  dilute 
nitric  acid,  to  the  vapor  of  iodine  ;  an  extremely  thiu  coat  of  iodide  of 
silver  will  be  formed.  Place  the  plate  in  the  Camera  Obscura  for  eight 
or  ten  minutes,  in  such  a  position  that  the  light  may  come  from  the 
object,  and  an  image  of  it  be  formed  on  the  plate;  then  expose  it,  at  an 
angle  of  4d°,  to  the  vapor  of  mercury ;  Ireat  it  to  107°  Fahr.,  and  the 
iiJKt^rs  will  appear.  The  plate  should  then  be  exposed  to  the  action  of 
hyposulphite  of  soda,  and  washed  in  a  large  quantity  of  distilled 
water* 

Magnetic  Rays.  Dr.  Morrichini,  of  Rome,  discovered 
that  the  more  refrangible  rays  possessed  the  property  of 
rendering  iron  magnetic;  Mrs.  Somerville  confirmed  this 
statement  by  magnetizing  a  sewing  needle  with  less  than 
two  hours'  exposure  to  th'e  violet  rays;  but  others  have  not 
been  so  successful,  and  it  is  questionable  whether  these  rays 
possess  this  property. 

V.  Absorption.  The  rays  of  light  are  separated  by  ab- 
sorption. When  light  falls  upon  a  substance,  more  or  less 
of  it  disappears  like  sensible  caloric. 

1.  The  different  colors  are  absorbed  variously  by  .different 
surfaces.  This  is  the  cause  of  the  great  variety  of  colors  ; 
for,  when  all  the  rays  are  absorbed  except  the  red,  and  these 
only  reflected,  the  body  is  red.  Thus,  in  colored  bodies,  only 
a  part  of  the  rays  can  be  reflected  ;  and  to  the  admixture  of 
the  different  colors  in  the  reflected  portion,  is  owing  all  the 
beautiful  variety  of  color. 

'2.  The  absorption  of  light  varies  with  the  chemical  consti- 
tution ;  hence,  by  the  action  of  chemical  agents  upon  each 
other,  every  variety  of  color  can  be  produced  at  pleasure. 

E.rp.  Into  a  little  chloride  of  calcium,  in  solution,  pour  a  few  drops 
of  sulphuric  acid;  a  white  solid  will  be  formed. 

Er.p.  Into  a  dilute  solution  of  persulphate  of  iron  pour  the  tincture 
of  gull ;  fine  black  ink  will  be  formed. 

Exp.  Into  an  infusion  of  purple  cabbage  put  a  drop  or  two  of  sul- 
phuric acid ;  a  beautiful  red  will  be  produced. 

Exp.  Nitrate  of  mercury  and  infusion  of  gall  will  form  an  orange 
colnr. 

£./•;>.    Nitrate  of  lead  and  hydriodic  acid,  yellow. 

Exp.    Vegetable  infusion  and, an  alkali,  green. 

Exp.   Aquae  ammonia  and  sulphate  of  copper,  blue. 

/,*>/;.    Ferro-cyanuret  of  potasaa  and  sulphate  of  iron,  indigo. 

E.cp.    Red  and  indigo,  mixed,  form  vk>let. 

3.  When  all  the  rays  are  absorbed,  so  that  none  can  be 
reflected,  the  body  is  black  ;  for  the  same  reason,  everything 

*  See  Jour.  Franklin  Inst.  XXIV.  207. 


70  Light.  —  Ignition  —  Phosphorescence. 

is  black  in  total  darkness.     If  none  of  the  rays  are  absorbed, 
and  all  are  reflected,  the  body  is  white.* 

VI.  Ignition    and  Incandescence.      The   phenomena   of 
ignition   and  incandescence    include  all  kinds   of   artificial 
light,  which  is  obtained  by  the  combinations  of  inflammable 
matter,  or   the    heating  of  non-combustible  bodies.     Solids 
begin  to  emit  light  in   the  dark  at  700°,  and  in  the  light  at 
1000°  F.     Gases  require  a  higher  temperature;  flame  is  in- 
candescent gas.     The  color  of  the  rays  depends  upon  the 
kind  of  substances  and  the  degree  of  heat:  the   white  light 
of  oil,  candles,  etc.,  when  transmitted  through  a  prism,  has 
but   three   primary    colors — red,   yellow    and  green.     The 
dazzling  light  emitted  by  lime  intensely  heated,  gives   the 
prismatic   colors    almost    as   bright   as   the  solar  spectrum. 
Different  substances  assume  different  colors  when  intensely 
heated.     Chemical  rays  exist  very  feebly  in  most  artificial 
light,  but  in  the  intense  light  of  lime,  under  the  compound 
blowpipe,  they  are  more  easily  detected. 

VII.  Phosphorescence :     There  are   many    substances    in 
nature   which  possess  the  property  of  shining  in  the  dark, 
without  the  emission  of  caloric.     These  are  said  to  be  phos- 
phorescent, and  are  known  by  the  term  phosphori,  (although 
there  is  no  phosphorus  connected  with  the  phenomena.) 

1.  Solar  Phosphori.  Many  bodies  acquire  this  property  on  exposure 
to  the  solar  rays  for  a  few  hours.  Such,  for  example,  is  Canton's  phos- 
phorus, a  composition  made  by  mixing  three  parts  of  calcined  oyster 
shells  with  one  of  the  flowers  of  sulphur,  and  exposing  the  mixture 
for  an  hour  to  a  strong  heat  in  a  covered  crucible.  Chloride  of  r;-l- 
cium  (Homberg's  phosphorus)  possesses  the  same  property ;  also, 
nitrate  of  lime,  (Baldwin's  phosphorus,)  and  a  variety  of  other  sub- 
stances, such  as  carbonate  of  baryta,  strontia  and  lime,  the  diamond, 
fluor-spar  or  chlorophane,  apatite,  boracic  acid,  etc.  Scarcely  any 
phosphori  act  unless  they  have  been  exposed  to  light. 

When  phosphorescence  ceases,  it  can  be  restored  by  a 
second  exposure  to  the  light,  or  by  passing  electric  dis- 
charges through  the  substance. 

2.  Phosphorescence  from  Moderate  Heat.  Chlorophane 
and  several  mineral  substances  require  to  be  heated  before 

*  Colors  have  an  important  influence  on  the  absorption  and  disen- 
gagement of  odorous  matters.  White  bodies  are  the  least  absorbent, 
and  dark  the  most  so. 


Photometers.  71 

they  phosphoresce.  Lime  is  a  remarkable  instance ;  when 
heated,  it  gives  out  a  dazzling  white  light,  too  intense  to 
look  upon  without  injury  to  the  eyes.  Light  is  also  emitted 
during  the  crystallization  of  many  salts,  as  the  sulphate  of 
potassa  and  fluoride  of  sodium. 

Exp.  Put  three  drachms  of  the  vitreous  arsenous  acid  into  a  matrass, 
with  an  ounce  and  a  half  of  hydrochloric  acid,  and  half  an  ounce  of 
water;  boil  the  mixture  for  ten  minutes,  and  then  suffer  it  to  cool 
slowly.  When  crystallization  commences,  each  little  crystal  will  be 
attended  by  a  spark ;  on  sudden  agitation,  great  numbers  of  crystals 
shoot  up,  accompanied  with  an  equal  number  of  sparks ;  if  larger 
quantities  are  taken,  and  the  vessel  shaken  at  the  right  moment,  the 
emission  of  light  is  so  powerful  as  to  illuminate  a  dark  room. 

3.  Animal  and  Vegetable  Phosphori.  Some  animal  and 
vegetable  substances  emit  light  at  common  temperatures, 
without  exposure  to  the  sun's  rays.  This  property  is  re- 
nrirkable  in  some  fish,  as  the  mackerel ;  the  light  makes  its 
appearance  just  before  putrefaction  commences,  and  ceases 
when  it  is  completely  established.  Some  species  of  decayed 
wood  possess  this  property  in  a  remarkable  degree. 

VIII.  Photometers.     It  is  sometimes  desirable  to  measure 
the  intensity  of  light,  emitted  from  different  objects,  and  an 
instrument  has  been   invented   for  this  purpose,  called  the 
Photometer,  or  light  measurer.     The  principal  one  employed 
for  this  purpose  is  that  of  Leslie. 

It  consists  of  a  very  delicate  and  small  differential  ther- 
mometer, one  bulb  of  which  is  made  of  black  glass,  and  the 
whole  is  enclosed  in  a  small  glass  tube.  The  white  ball 
transmits  all  the  light  and  heat,  and  is  of  course  unaffected ; 
the  black  ball  absorbs  all  the  rays,  and  heats  the  air  within, 
so  as  to  cause  the  liquid  to  rise.  Its  action  of  course  depends 
upon  the  heat  produced  by  the  absorption  of  light. 

Some  objections  to  this  instrument  have  been  stated  by 
Turner. 

Count  Rumford's  Photometer  determines  the  comparative 
strength  of  lights,  by  a  comparison  of  the  shadows  of  bodies. 

Sources  of  Light.  These  are  similar  to  those  of  caloric  — 
the  sun,  stars,  chemical  action,  mechanical  action,  and  caloric. 

IX.  Nature  of  Light.     Light  and  caloric  have  been  re- 
garded by  some  as  identical.     Newton  supposed  that  light 


72  --     Electricity. 

was  a  material,  subtile  fluid,  which  emanated  from  luminous 
bodies  in  all  directions  in  right  lines,  and  produced  the  sen- 
sation of  vision,  by  falling  upon  the  retina  of  the  eye;  this 
is  termed  the  Newtonian  theory.  But  Descartes,  Huygens, 
and  Euler,  proposed  a  different  theory,  which  has  been  lately 
revived  by  Sir  John  Herschel  and  Prof.  Airy.  This  theory 
supposes  that  light  is  produced  by  vibrations  in  an  elastic 
medium,  which  pervades  all  space,  and  that  vision  is  the 
effect  of  these  vibrations,  meeting  the  retina,  in  the  same 
manner  as  pulsations  of  air  impress  the  nerve  of  hearing, 
and  produce  the  sensation  of  sound.  At  present,  the 
strongest  evidence  is  in  favor  of  this  theory,  which  has 
received  the  name  of  the  undulatory  theory.  (See  Sir  J. 
Herschel's  article  on  Light  in  the  Encyclopedia  Mi-tro/ml- 
itana.)  Either  of  the  above  theories  answers  the  purpose  of 
classifying  the  facts,  and  it  is  not  material  which  is  adopted. 


CHAPTER    III. 

ELECTRICITY. 

The  word  electricity  is  derived  from  the  Greek  name  for 
amber,*  a  substance  which  possessed  the  property  of  at- 
tracting light  bodies  when  rubbed. 

1.  If  a  piece  of  sealing-wax,  or  a  glass  rod,  be  rubbed  with  a 
dry  woollen  or  silk  cloth,  each  becomes  capable  of  attracting 
and  repelling  light  substances.     In  this  state  each   is  said 
to   be  electrified,  or  electrically  excited.     When  friction   is 
applied  to  many  other  substances,  they  exhibit  similar  phe- 
nomena.    The  cause  of  this  attraction  and   repulsion  is  as- 
cribed to  an  agent  called  electricity,  and  when  it  is  excited 
by  friction,   it  is  designated   by   the  title  of  common  elec- 
tricity. 

2.  If  a  plate  of  copper  and  a  plate  of  zinc,  having  copper 
wires  soldered  to  each,  be  immersed  in  acidulated  water, 
and  the  ends  of  the  wires  brought  into  contact,  they  will 

*  HlexTQov. 


Common  Electricity.  73 

exhibit  similar  phenomena  of  attraction  and  repulsion.  When 
electricity  is  excited  in  this  way,  there  is  always  a  chemical 
action  between  the  metal  and  the  liquid,  and  it  is  called 
Galvanism,  in  honor  of  Galvani,  who  made  the  discovery; 
also  Voltaic  electricity,  from  Volta,  who  first  demonstrated 
its  existence  as  independent  of  the  animal  system. 


SECT.   1.  COMMON  ELECTRICITY. 

Common  electricity  is  generally  excited  by  the  friction  of 
one  substance  upon  another. 

1.  If  a  piece  of  sealing  wax,  or  any  resinous  substance,  be 
rubbed   with  a  silk   cloth,  and   a  pith  ball,  suspended   by  a 
thread,  be  brought  near  it,  the  ball  will  be  at  first  attracted, 
and  then  repelled. 

2.  If  a  rod  of  glass,  or  other  vitreous  substance,  be  rubbed 
in  a  similar  manner,  and  brought  near  the  ball,  it  will  attract 
it,  while  the  seahng-wax  will  repel  it. 

3.  If  two  balls  be  each  electrified  by  the  sealing-wax,  or 
by  the  glass;  they  will  repel  each  other ;  but  if  one  is  electri- 
fied by  the  wax,  and  the  other  by  the  glass,  they  will  attract 
each  other  ;  hence,  when  friction  is  applied  to  resinous  and 
vitreous  bodies,  opposite  effects   are  produced.     The  state 
induced  by  friction  upon  the  glass,  was  called  by  Dr.  Frank- 
lin positive,  and  that  induced  upon  the  wax  negative,  and  the 
substances  were  said  to  be  positively  or  negatively  electrified. 

Theories.  1.  Franklin. supposed  that  electricity  pervaded 
matter  generally,  and  that  friction  tended  to  bring  it  upon 
the  surface  of  bodies,  or  drive  it  from  them ;  that  it  was  in 
its  nature  self-repellent,  but  possessed  a  powerful  attraction 
for  common  matter;  when  a  body  was  electrified  positively, 
it  had  more  than  its  share  of  electricity ,  when  it  was  electri- 
fied negatively,  it  had  less  than  its  natural  portion. 

2.   Du  Fay  supposed  that  there  were  two  fluids :  the  one  de- 
veloped by  the  friction  of  the  glass  he  called  vitreous,  which 
.  answers  to  the  positive  electricity  of  Franklin,  and  the  other, 
developed  by  the  friction  of  the  wax,  he  called  resinous,  which 
corresponds  with  the  negative  electricity  of  Franklin.     Each 
7 


74  Electricity.  —  Gold  Leaf  Electrometer. 

fluid  repels  itself,  and  attracts  the  other.  It  follows  from 
this  theory,  that  substances  electrified  by  the  same  fuid  r<pdy 
and  those  electrified  by  the  opposite  fluids  attract,  each  other, 
and  friction  only  tends  to  separate  them. 
.  The  existence  of  the  two  fluids  may  be  shown  Fig.  29. 
by  the  Gold  Leaf  Electrometer  *  (Fig.  29,)  which 
consists  of  two  strips  of  gold  leaf  suspended  by  a 
brass  cap  and  wire,  in  a  glass  cylinder.  When 
electrified  with  either  kind  of  electricity,  the  leaves 
diverge. 

But  if,  when  the  leaves  diverge  with  negative 
electricity,  a  substance  excited  positively  be  brought 
near,  the  leaves  will  collapse. 

Exp.  Bring  excited  sealing-wax  in  contact  with  the  brass  knob  «, 
the  leaves  will  diverge  with  negative  electricity.  Place  now,  excited 
glass  upon  the  knob,  and  the  leaves  will  come  together,  because  the 
positive  fluid  restores  the  equilibrium.  If  pith  bulls  be  suspended  by  a 
wire  or  thread,  similar  effects  may  be  produced. 

Some  substances,  such  as  glass  and  resin,  retain  the  elec- 
tricity upon  their  surfaces  when  excited,  and  are  hence  called 
non-conductors  of  electricity. 

Other  substances,  as  the  metals,  do  not  retain  electricity 
upon  their  surfaces,  unless  they  are  surrounded  by  non-con- 
ductors, but  convey  it  away,  or  oppose  no  barriers  to  the 
union  of  the  two  fluids ;  such  bodies  are  called  conductors  of 
electricity.  The  metals  are  all  conductors;  dry  air,  gla.-s, 
sulphur,  and  resins,  are  non-conductors;  water,  damp  wood, 
moist  air,  alcohol,  and  some  oils,  are  imperfect  conductors. 
The  non-conductors  are  called  insulators. 

Some  substances  exhibit  signs  of  electricity  when  heated, 
such  as  tourmalin,  topaz,  diamond,  beryl. 

Electrical  Machine.  The  instrument  by  which  the  phe- 
nomena of  common  electricity  may  be  best  exhibited,  is  the 
electrical  machine  i  (Fig.  30,)  which  consists  of  a  cylinder, 
or  plate  of  glass  G,  revolving  on  an  axis,  and  subjected  to  the 
friction  of  a  rubber  R  of  leather  or  silk,  upon  which  is 
spread  a  thin  coat  of  amalgam,  composed  of  tin,  mercury, 

*  HXexTQov  and  ^ST^OV,  a  measurer  of  electricity. 

t  In  the  absence  of  an  electrical  machine,  many  experiments  may  be 
performed  with  a  rod  of  glass,  or  sealing-wax,  two  inches  in  diameter, 
and  rubbed  with  a  silk  handkerchief. 


Electrical  Machine. 
Fig.  30. 


75 


insulated  by  a  glass  pillar,  nnd  communicates  with  the  ground 
!>v  a  brass  chain,  C.  Attached  to  the  machine  is  a  cylindrical 
metallic  conductor,  P,  which  is  also  insulated  by  a  glass  pillar. 
When  the  machine  is  in  operation,  vitreous  electricity 
flows  from  the  rubber  and  glass,  by  means  of  fine  points,  to 
the  prime  conductor,  P,  and  resinous  electricity  passes  in  an 
opposite  direction.  If  the  hand  be  placed  upon  the  con- 
ductor, currents  of  electricity  will  pass  in  opposite  directions, 
the  vitreous  passing  into  the  body  from  P,  and  the  resinous 
down  the  chain  G  to  the  ground.  But  if  the  hand  be  held 
at  a  little  distance  from  the  conductor,  a  spark  will  dart 
though  the  air,  and  cause  a  prickling  sensation,  accompanied 
by  a  slight  report,  with  light  and  heat.  The  sound  is  pro- 
duced by  the  collapse  of  the  air,  as  the  fluid  forces  a  passage 
through  it;  and  the  light  and  heat  are  supposed  to  result  from 
the  sudden  condensation  of  the  air,  as  in  the  fire  syringe. 

Induction.  If  an  insulated  body  be  brought  near  the  prime 
conductor,  it  will  manifest  signs  of  electricity  opposite  to 
that  of  the  conductor,  on  the  side  nearest  the  conductor,  and 
similar  to  the  conductor  on  the  other  side,  while  the  centre 
of  the  body  will  be  neutral.  The  electricity,  in  this  case,  is 
induced  by  the  presence  of  the  electrified  conductor;  and 


76  Electricity.  —  Induction  —  Theory. 

the  process  is  called  induction.  Several  insulated  conductors 
placed  contiguous,  will  exhibit  the  same  phenomena  if  a 
communication  be  made  between  the  last  and  the  ground. 

Thus,  (Fig.  31,)  Fig.  31. 

let  A  represent  the 
positive  conductor 
of  an  electric  ma- 
chine, b  and  c  in- 
sulated conductors, 
with  a  chain  pass- 
ing to  the  ground. 

The  conductor  b  will  be  electrified  by  induction,  as  will  he 
indicated  by  the  attached  balls.  Thus  1,  being  positive,  will 
attract 'the  balls  2,  which  are  rendered  negative  by  induction. 
The  balls  3  are  also  rendered  positive,  4  negative,  and  «"> 
positive,  while  the  centres  b  c  will  remain  neutral. 

Theory.  The  phenomena  of  induction  led  Faraday  to 
propose  a  theory  of  attraction  and  repulsion.  The  reason 
why  an  excited  body  attracts  another  is,  that  it  induces  in 
it  an  opposite  electrical  state.  He  considers  induction  an 
essential  function,  both  in  \he  development  and  continuance 
of  electrical  currents;  that  it  consists  in  a  polarized  state  of 
the  particles,  or  positive  and  negative  points,  induced  by  the 
presence  of  an  electrified  body. 

Application  of  the  Theory.  According  to  this  theory,  an 
excited  body  attracts  light  substances,  because  it  induces  in 
them  an  opposite  state  of  electricity. 

1.  On  moving  the  hand  towards  the  prime  conductor,  it  is 
electrified  negatively  by  induction  ;  when  a  spark  is  received, 
the  equilibrium  is  restored. 

2.  When    a   cloud,   positively   or    negatively    electrified, 
passes  over  a  tower,  or  a  tree,  it  induces  an  opposite  state  in 
them,  and  a  stroke  of  lightning  follows  in  consequence  of  the 
attraction   between  the  two  accumulated   fluids ;  hence  the 
utility  of  lightning-rods  to  form  a  communication  between 
the  clouds  and  the  ground. 

3.  The  action  of  the  Leyden  Jar  is  due  to  induction.     It 
consists  of  a  glass  jar,  lined  on  the  inner  and  outer  surfaces, 
save  a  few  inches  near  the  mouth,  with  tin  foil.     Through  the 
stopper,  made  of  dry  wood  or  sealing-wax,  a  brass  rod  com- 


Electrometers. 


77 


Fig.  32. 


municates  with  the  inner  surface.  When  positive  electricity 
is  applied  to  the  inside,  it  drives  off  the  same  fluid  on  the 
outer  surface,  and  induces  the  negative  fluid.  These  fluids 
exert  a  strong  mutual  attraction  upon  each  other,  through 
the  glass,  and  enable  both  to  accumulate  in  larger  quantities 
than  they  would  do  on  separate  conductors.  When  a  com- 
mimic-ition  is  made  between  the  inner  and  outer  surfaces, 
the  equilibrium  is  suddenly  restored,  accompanied  by  a 
sharp  report.  When  several  jars  are  connected  by  their 
outer  surfaces,  and  also  by  their  inner  surfaces,  they  consti- 
tute an  electrical  battery. 

4.  The  action  of  the  Ekctrophorus 
(bearer  of  electricity)  (Fig.  32)  de- 
pends upon  the  same  principle.  It  may 
be  constructed  by  pouring  melted  resin 
into  the  cover  of  a  firkin,  taking  care, 
\viicn  it  cools,  to  render  the  surface  even. 
Ad  ipt  to  this  a  circular  piece  of  board 
covered  with  tin  foil,  and  fix  a  glass  rod 
in  1  lie  centre  for  a  handle.  This  instru- 
ment may  be  used  instead  of  the  machine  for  charging  Ley- 
d'2n  Jars. 

Electrometers,  or  Electroscopes,  These  are  instruments  for 
detecting  the  presence  of  electricity,  as  in  the  Gold  Leaf 
Electrometer,  (page  74,)  or  for  determining  the  degree  of  its 
tension,  or  attracting  and  repelling  power.  For  this  last 
purpose,  the  Balance  Electrometer  is  used. 


Thus  A  (Fig.  33)  is  a  Leyden  jar,  which  may  be  con- 

7* 


78'       Laws  of  the  Accumulation  of  the  Electric  Fluid. 

nected  with  the  prime  conductor  of  an  electric  machine ;  B, 
a  brass  ball  connected  with  D,*  E ;  C,  another  ball,  with  a 
chain,  G,  connecting  it  with  the  table  or  the  outside  of  the  jar  ; 
D,  a  brass  rod  balanced  at  the  centre,  and  insulated  by  the  glass 
post  H  ;  E  is  a  ring  which  may  be  placed  at  any  distance 
from  F,  bringing  the  ball  in  contact  with  B.  If,  now,  the  jur 
be  positively  electrified,  the  ball  on  the  end  of  E  will  be  re- 
pelled, C  will  be  electrified  negatively  by  induction^  and 
there  will  be  a  powerful  attraction  between  C  and  the  ball 
on  the  end  of  D,  which  will  bring  them  together,  and  the 
equilibrium  will  be  restored.  The  force  of  attraction  will  be 
measured  by  the  distance  between  the  balls  and  the  weight 
applied  at  E.  With  a  powerful  electrical  battery,  successive 
vibrations  may  be  produced  in  the  beam,  and  a  bright  spark 
and  loud  report  produced  at  each  contact  of  the  balls. 

Laws  of  the  Accumulation  of  the  Electric  Fliti-.!. 

1.  Free  electricity  is  always  accumulated  upon  the  surface 
of  an  insulated  conductor,  and  does  not  penetrate  its  Mib- 
stance ;  hence  the  quantity  does  not  depend  upon  the  t/iftinflti/ 
of  matter  in  the  conductor,  but  upon  the  extent  of  surface. 

2.  The  mode  in  which  electricity  is  distributed  over  the 
surface  of  conductors,  depends  upon  their  form.    On  a  sphere, 
it  forms  a  uniform  stratum.-  On  an  ellipsoid,  the  stratum  is 
thickest  on  the  extremities  of  the  longer  axis,  and,  as  these 
extremities  approach  to  the  form  of  points,  the  accumulation 
increases  till  the  tension  becomes  so  great,  that  it  flows  off 
into  the  atmosphere;  hence  electricity  cannot  be  retained  on 
a  conductor  which  has  points  attached  to  it. 

3.  This  tendency  to  escape  is  due  to  the  repulsion  of  its 
particles. 

4.  Coulomb  proved  by  his  Torsion  Electrometer,  that  the 
repulsion  of  two  bodies  similarly  electrified,  and  the  attraction 
of  two  oppositely  electrified,  varies  inversely,  as  the  square 
of  the  distance  between  them. 

SECT.  2.    VOLTAIC  ELECTRICITY,  OR  GALVANISM. 

History.  In  the  year  1791,  Galvani,  an  Italian  Professor 
of  Anatomy  at  Bologna,  discovered  that  if  a  silver  probe  were 
made  to  touch  the  crural  nerve  of  a  recently  killed  frog,  and 
a  strip  of  zinc  the  muscle,  violent  contractions  would  be  pro- 
duced at  each  contact  of  the  two  metals  —  the  same  effect  as 


Simple   Voltaic  Circles.  79 

is  produced  by  an  electric  spark.  Hence  he  concluded  that 
the  phenomena  were  due  to  electricity,  generated  by  the 
animal  system.  Some  years  after,  Prof.  Volta,  of  Pavia,  dis- 
covered that  the  animal  system  was  not  necessary  to  the  de- 
velopment of  this  kind  of  electricity,  which  he  proved  by  the 
construction  of  a  pile  of  insulated  plates,  of  different  metals, 
called  the  Voltaic  pile.  This  discovery  has  given  to  this  form 
of  exciting  electricity  the  epithet  voltaic. 

But  the  identity  of  the  agent  concerned  in  galvanism,  and 
of  that  in  the  common,  electrical  machine,  is  now  a  matter  of 
demonstration.  Magnetism  is  doubtless  due  to  the  same 
agent,  and  probably  chemical  affinity,  which  reduces  the  four 
subjects  to  one,  and  renders  it  much  more  simple,  and  easy 
to  classify  effects  which  were  once  supposed  to  originate  from 
as  many  distinct  agents. 

I.  Simple  Voltaic  Circles.  Erp.  Place  a  piece  of  zinc 
upon  the  tongue,  and  a  piece  of  silver  under  it :  whenever  the 
projecting  edges  of  these  metals  are  brought  into  contact,  a 
peculiar  sensation  will  be  perceived,  and,  if  the  plates  are 
large  enough,  a  flash  of  light.  This  effect  is  not  due  to  elec- 
tricity generated  by  the  animal  system,  but  to  that  developed 
in  the  metals;  for  if  the  sa-ne  plates,  Fie.  34. 

or  larger  plates,  be  placed  in  water, 
(Fig.  34,)  and  the  connection  made, 
electricity  will  be  excited;  feeble  in- 
deed, but  in  sufficient  quantities  to  be 
detected  by  a  proper  apparatus.  If, 
however,  a  few  drops  of  sulphuric  or 
nitric  acid  be  added  to  the  water,  and 
the  ends  of  the  plates  C  and  Z  brought 
into  contact  directly,  or  by  means  of  wires  soldered  to  the 
plates,  bubbles  of  hydrogen  gas  will  rise  from  the  surface  of 
the  copper  plate  C,  and  electricity  will  be  developed  in  larger 
quantities.  The  currents  will  continue  to  circulate  from  one 
plate  to  the  other,  as  long  as  the  ^ires  are  kept  in  contact, 
but  will  cease  when  they  are  separated.  This  is  a  case  of  a 
simple  voltaic  circle.  The  direction  of  the  positive  current 
is  indicated  by  the  position  of  the  arrows.  When  the  wires 
are  in  contact,  the  circuit  is  said  to  be  closed,  and  a  current 
of  positive  electricity  flows  through  the  water  from  the  zinc 
plate  Z  to  the  copper  C,  and  from  the  copper  along  the  con- 


80  Electricity.  —  Compound  Voltaic  Circles. 

ducting  wires  to  the  zinc.  A  current  of  negative  electricity, 
on  the  theory  of  two  fluids,  passes  in  an  opposite  direction. 
When  the  wires  are  separated,  the  circuit  is  said  to  be  broken. 

The  contact  may  be  made  above  the  water,  or  in  it,  or  the 
plates  may  touch  each  other  throughout,  or  be  soldered  to- 
gether; in  either  case  electricity  will  be  excited;  but  if  one 
plate  is  out  of  the  liquid,  no  currents  can  be  produced. 

A  simple  voltaic  circle  may  be  formed  of  one  metal  and 
two  liquids,  provided  a  stronger  chemical  action  is  induced  on 
one  side  of  the  plate,  than  on  the  other.  Simple  voltaic  cir- 
cles may  also  be  formed  of  vari<  .s  materials ;  but,  generally, 
they  consist  of  one  perfect  and  two  imperfect  conductors 
of  electricity,  or  of  two  perfect  and  one  imperfect  conductors. 

Metals  and  prepared  charcoal  are  perfect,  water  and 
aqueous  solutions  imperfect  conductors.  But,  whatever  be 
the  construction,  chemical  action  seems  absolutely  necessary 
to  the  development  of  voltaic  currents. 

The  most  common  and  convenient  form 
of  the  simple  battery,  is  that  of  two  cyl- 
inders of  copper,  C,  (Fig.  35,)  the  one 
within  the  other,  separated  about  one 
inch,  with  a  bottom  soldered  on,  so  as  to 
contain  the  exciting  liquid,  a,  between 
them,  and  a  cylinder  of  zinc,  Z,  placed 
between  the  two  cylinders  of  copper,  and  insulated  by  ivory 
handles.  The  two  plates  are  furnished  with  wires,  terminated 
by  the  cups  b  6,  which  contain  a  globule  of  mercury.  The 
connection  is  made  by  means  of  wires  dipped  into  the  mercury 
in  the  cups.  Or,  the  copper  and  zinc  may  be  coiled  around 
each  other,  so  that  each  surface  of  zinc  may  be  opposed  to 
one  of  copper,  but  separated  from  it  by  a  small  interval. 
By  thus  exposing  a  large  surface  of  zinc  to  a  similar  sur- 
face of  copper,  Dr.  Hare  was  enabled  to  melt  the  most 
refractory  metals,  and  from  this  circumstance  gave  it  the 
name  of  Calorimotor. 

II.  Compound  Voltaic  Circles.  Compound  circles  consist 
of  a  series  of  simple  circles,  for  the  purpose  of  increasing 
the  intensity  of  voltaic  currents.  The  first  combination  of 
this  kind  was  made  by  Volta,  and  is  called  the  voltaic  pile. 


Compound   Voltaic  Circles. 


81 


1.  This  pile  consists  of  zinc  and  copper  plates,      Fig.  36. 
(Fig.  36,)  placed  alternately  one  above  another, 

with  strips  of  woollen  cloth  moistened  with  salt 
water  between  each  pair.  By  connecting  the  top 
and  bottom  plates,  currents  of  electricity  will  be 
set  in  motion. 

2.  But  other  forms  of  voltaic  circles  are  now 
in  use.     The  most  convenient  is  that  invented 
by    Wollaston.     It    consists  of  any    convenient 
number  of  zinc  and  copper  plates,  so  arranged, 

that  each  zinc  plate  is  surrounded  by  two  of  copper. 

A  (Fig.  37)  is  a  trough  to  contain  the  exciting  liquid ;  B 
a  case  passing  around  the  plates,  and  -connected  by  chains  to 
the  windlass  C,  by  means  of  which  the  plates  can  be  lowered 
into  the  liquid,  or  raised  to  any  position  required.*  EE  are 
small  hand-vices  attached  to  the  poles.  The  zinc  plates  are 
confined  in  copper  cases,  insulated  by  wood  at  each  end. 
The  copper  cases  are  separated  £  of  an  inch,  by  pasteboard, 
which,  with  the  wood,  is  saturated  by  oil  and  wax.  The 
connection  between  the  zinc  and  copper  plates  is  made  by 
strips  of  copper  soldered  to  the  zinc  of  one  pair,  and  to  the 
copper  of  the  adjacent  pair;  by  this  construction,  the  power 
of  the  battery  is  increased  nearly  one  half. 

Fig.  37.  - 


As  each  zinc  plate  is  connected  to  the  adjacent  copper 
plate,  the  currents  nre  urged  along  from  one  to  the  other,  in 
opposite  directions,  till  they  meet  at  the  poles. 

The  size  and  number  of  plates  may  be  varied  at  pleasure. 
The  largest  battery  ever  constructed  is  that  of  Mr.  Children, 


*  In  some  batteries,  the  plates  are  stationary,  and  the  trough  is  raised 
and  lowered.  This  is  the  most  convenient  construction,  especially  ia 
large  batteries. 


82  Electricity.  —  Theories  of  Galvanism. 

the  plates  of  which  were  6  ft.  long  and  2  ft.  8  inches  broad. 
The  most  convenient  size  is  4  inches  by  6.  A  battery  con- 
taining 200  or  300  plates,  and  thrown  into  vigorous  action,  is 
nearly  as  powerful  as  one  much  larger.*  The  battery  of 
Dr.  Hare  is  called  a  Deflagrator,  from  its  surprising  power 
of  burning  the  metals. 

The  direction  of  the  currents  in  this  apparatus  is  the  same 
as  in  the  simple  circles :  positive  electricity  passes  from  tfie 
zinc  through  the  liquid  to  the  copper  plates,  and  is  given  off 
at  the  copper  pole  of  the  battery,  while  negative  electricity 
takes  the  opposite  direction,  and  appears  at  the  zinc  or 
negative  pole. 

During  the  action  of  the  battery,  all  the  hydrogen  evolved 
in  the  process  is  given  off  at  the  surface  of  the  copper,  and 
the  weight  of  the  hydrogen  during  any  given  time,  and  thnt 
of  the  zinc  dissolved,  will  be  as  1  to  32.8,  which  is  the  ratio 
of  their  chemical  equivalents.  This  shows  the  close  con- 
nection between  electricity,  thus  excited,  and  chemical 
affinity. 

Theories  of  Galvanism. 

On  this  subject  there  are  three  theories:  1.  The  first 
originated  with  Volta,  who  conceived  that  electric  currrnts 
are  set  in  motion,  and  kept  up,  solely  by  contact  of  the  dif- 
ferent metals.  He  regarded  the  interposed  solution  merely 
as  a  conductor  to  convey  the  electricity  from  one  point  to 
another. 

2.  The  second  theory  was  proposed  by  Dr.  Wollaston, 
who  supposed  that  chemical  action  was  the  sole  cause  of 
exciting  and  continuing  the  voltaic  currents;  and  the  fact 
that  no  sensible  effects  are  produced  by  a  combination  of 
conductors,  which  do  not  act  chemically  upon  each  other,  is 
the  strongest  proof  of  its  truth :  even  in  the'  voltaic  pile, 
the  energy  of  the  action  depends  upon  the  oxidation  of  the 
zinc. 


*  In  experimenting  with  the  battery,  the  plates  should  not  be  im- 
mersed in  the  liquid  but  a  few  minutes  at  a  time  ;  by  raising1  and  low- 
ering them  for  each  experiment,  their  vigorous  action  will  be  kept  up 
much  longer  ;  or  the  troughs  may  be  so  constructed,  that,  by  a  partial 
icvolution,  the  exciting  liquid  may  be  withdrawn  from  the  plates,  or 
thrown  upon  them  at  pleasure. 


Laws  of  the  Action  of  Voltaic  Circles.  83 

3.  The  third  theory  was  suggested  by  Sir  H.  Davy,  and  is 
intermediate  between  the  two  preceding.  He  supposed  that 
the  electric  equilibrium  was  disturbed  by  contact  of  the 
metals,  and  the  electric  currents  kept  up  by  chemical  action. 

The  theory  of  Wollaston  is  now  generally  embraced. 

Laws  of  the  Action  of  Voltaic  Circles. 

Electricians  distinguish  between  quantity  and  Intensity  in 
Galvanism,  as  in  ordinary  electricity. 

Quantity  refers  to  the  amount  of  the  electric  fluid  set  in 
motion;  tension,  or  intensity,  to  the  energy  or  effort  with 
which  a  current  is  iaipelled.  Common  electricity  has  great 
tension;  voltaic,  great  quantity,  —  and  this  is  the  principal 
difference  between  them. 

1.  In  the  broken  circuit,  there  is  a  strain  to  establish  ;in 
electric  current,  because  without  this,  oxidation  cannot  take 
place.     Tiiere  exists  between  the  exciting  fluid  and  the  zinc, 
a  desire,  as  it  were,  for   chemical  action,  which  cannot   be 
gratified  until,  by  closing  the  circuit,  a  door  is  opened  for  the 
escape  and  circulation  of  electricity.     This  strain  or  tension 
is  great,  according  as  the  affinity  between  the  exciting  fluid 
and  the   zinc  is  great.     Currents  of  high  tension  are  urged 
forward  with  greater  impetuosity  than  feeble  one's,  and  hence 
they  more  readily  overcome  obstacles  to  their  passage. 

2.  Currents  from  a  single  pair  of  plates  have  not  a  hi^h 
A  7?s/Vw;  but  if  the  plates  are  large,  a  great  quantity  of  elec- 
tricity is  set  in  motion. 

The  condition  which  causes  a  high  tension  is  an  extended 
liquid  conductor,  along  the  whole  line  of  which  successive 
pairs  of  plates  are  arranged ;  each  acted  upon  chemically  by 
the  exciting  liquid,  and  urging  on  the  current  in  the  same 
direction.  But  the  quantity  in  this  case  may  not  be  great ; 
for,  although  its  tension  is  increased  by  the  force  which  each 
plate  gives  to  the  current  as  it  passes,  the  quantity  which 
passes  along  the  wire,  according  to  Faraday,  is  exactly  equal 
to  that  which  passes  through  one  of  the  cells  in  which  the 
plates  are  immersed. 

3.  The  energy  of  voltaic  currents  is  measured  either  by 
their  power  of  deflecting  a  magnetic  needle,  or  by  that  of 
chemical  decomposition.     The  deflection  of  the  needle  depends 


84  Electricity.  —  Effects  of  Galvanism. 

upon  quantity;  hence  a  single  pair  of  plates  will  deflect  the 
needle  more  than  a  number  of  small  ones  combined ;  but  de- 
composition depends  upon  quantity  and  intensity  together. 
The  decomposing  power  of  the  battery,  however,  does  not 
increase  in  the  ratio  of  the  number  of  plates,  but  as  the 
square  root  of  the  number,  so  that,  when  the  number  varies 
as  1  to  4,  the  decomposing  power  is  as  1  to  2. 

The  deflecting  power  of  a  single  pair  of  plates  varies  in- 
versely as  the  square  root  of  the  distance  between  them. 
Thus,  if  a  plate  of  zinc  be  placed  at  one,  four,  and  nine 
inches  from  a  plate  of  copper,  the  deflecting  powers  will  be 
in  the  ratio  of  3,  2,  1. 

4.  The  velocity  of  common  electricity  through  perfect  con- 
ductors, is  surpassed  only  by  that  of  light,  being,  according  to 
Wheatstone's  Experiments,  about  118,000  miles  per  second. 
From  some  experiments,  it  is  infered  that  the  velocity  of 
voltaic  electricity  is  somewhat  less.  Hence  this  agent  h;is 
been  employed  to  communicate  intelligence  from  one  place 
to  another.  The  Electro-Magnetic  Telegraph,  by  which  this 
is  effected,  depends  upon  the  velocity  of  electricity  and  its 
power  to  deflect  the  magnetic  needle. 

Effects  of  Galvanism. 

I.  The  effects  of  common  and  voltaic  electricity  have  many 
points  of  resemblance. 

1.  If  a  zinc  and  copper  plate  be  immersed  in  dilute  nitric 
acid,  and  the  wire  attached  to  the  zinc  plate  be  made  to 
touch  a  gold  leaf  electrometer,  the  leaves  will  diverge  with 
negative  electricity,  and  if  the  wire  of  the  copper  plate  be 
applied,  it  will  indicate  positive  electricity.     This  effect  is 
much  greater  when    a  battery  of  several  pairs   of  plates   is 
employed.     It  appears  to  be  due  to  the  disturbed  equilibrium 
in  the  zinc  plate ;  the  chemical  relation  of  which  to  the  acid 
renders  the  metal  positive,  at  the  expense  of  the  attached  wire, 
while  the  copper  plate,  induced  by  the  contiguous  zinc,  be- 
comes negative,  at  the  expense  of  its  wire,  which  becomes 
positive. 

2.  A  Lcyden  jar  may  be  charged  from  either  wire  of  an 
unbroken  circuit,  provided  a  large  quantity  of  electricity  be 
developed,  connected  with  high  tension.     This  effect  depends 
upon  the  number  of  plates  and  the  energy  of  the  action. 

3.  Voltaic,  like  common  electricity,  passes  through  the 


Effects  of  Galvanism.  85 

air,  and  other  non-conductors,  in  the  form  of  sparks,  accom- 
panied with  a  report,  and  the  development  of  light  and  heat. 
Hence  it  will  inflame  gunpowder,  phosphorus,  hydrogen  and 
oxygen,  and  other  inflammable  substances. 

4.  Its  tension,  however,  is  so  feeble,  compared  with  com- 
mon electricity,  that  it  has,  according  to  Mr.  Children,  a  very 
small  striking  distance;  i.  e.,  the  space  of  air  through  which 
the  spark  will  pass  is  comparatively  small.     With  a  battery 
of  1250  pairs  of  four-inch  plates,  he  found  the  striking  dis- 
tance to  be  ^\y  of  an  inch.     If  the  air  be  rarefied,  the  distance 
will  be  increased,  and  diminished  by  condensation. 

5.  The  effect  of  voltaic  electricity  upon  the  animal  sys- 
tem is  similar  to  that  of  common  electricity. 

6.  Both  kinds  also  deflect  the  magnetic  needle,  and  pro- 
duce chemical  decomposition. 

II.  One  of  the  most  surprising  effects  of  voltaic  currents 
is  their  power  of  igniting  the  metals. 

Exp.  Attach  to  each  pole  of  the  battery  strips  of  metallic  leaves, 
and  bring  them  in  contact ;  the  metals  will  burn  with  the  most  vivid 
scintillations.  (See  Fig.  37.) 

The  color  of  the  light  varies  in  different  metals.  Gold 
leaf  burns  with  a  white  light,  tinged  with  blue,  and  yields 
a  dark  brown  oxide.  Silver  emits  an  emerald-green  light, 
of  great  brilliancy  ;  copper,  a  bluish-white  light,  with  red 
sparks;  lead,  a  beautiful  purple  ;  and  zinc,  a  brilliant  white 
HI; lit,  tinged  with  blue  and  red.  If  the  communication  be 
made  with  charcoal  points,  (that  from  the  box-wood  is  the 
best,)  the  light  is  equal,  if  not  superior,  in  intensity,  to  that 
emitted  during  the  combustion  of  phosphorus  in  oxygen  gas, 
and  the  heat  is  sufficient,  it  is  said,  to  partially  fuse  the  car- 
bon, a  substance  which  is  fusible  by  no  other  means  of  pro- 
ducing heat.* 

Theory.  The  heating  power  seems  to  be  due,  for  the 
most  part,  to  the  quantity  of  electricity  developed  ;  hence,  for 
melting  wires,  a  calorimotor  is  preferable  to  a  compound  bat- 
tery. The  heat  is  supposed  to  arise  from  the  difficulty  with 
which  the  electric  currents  pass  along  the  conductors ;  but 

*  On  examining  the  points  after  they  have  been  subjected  to  the 
action  of  a  powerful  battery,  one  will  present  a  conical  appearance,  like 
the  head  of  a  pin,  the  other  a  corresponding  cavity.  The  matter  thus 
transposed  has  been  supposed  to  be  partially  melted ;  but  probably  it  is 
nothing  but  earthy  matter  in  the  carbon. 

8 


86       Electricity.  —  Chemical  Effects  of  Galvanism. 

as  the  substances  are  good  conductors,  the  effect  will  take 
place  only  when  the  quantity  of  electricity  transmitted,  is  out 
of  proportion  to  the  extent  of  surface  over  which  it  has 
to  pass. 

As  heat  and  light  are  produced  in  vacua,  under  water,  or 
in  gases  which  do  not  contain  combustible  matter,  these  phe- 
nomena cannot  be  attributed  to  combustion,  but  to  the  pro- 
duction of  light  and  heat  by  the  electric  fluid  itself.  The 
effects  of  common  electricity  from  the  electric  machine, 
and  in  the  case  of  lightning,  are  so  similar  to  those  above 
described,  that  there  can  be  no  doubt  of  the  identity  of  the 
agents  concerned  in  their  production. 

III.  Chemical  Effects  of  Galvanism.  The  phenomena 
which  accompany  chemical  combinations  are  similar  to  those 
produced  by  voltaic  electricity.  But  the  agency  .of  voltaic 
currents  to  effect  the  decomposition  of  chemical  compounds 
is  a  most  important  and  useful  discovery,  which  was  first  made 
by  Carlisle  and  Nicholson. 

1.  The  first  substance  decomposed  by  the  gal- 
vanic  battery  was  water.  The  water  for  decom- 
position is  put  into  a  small  vessel,  a,  (Fig.  38.) 
The  tubes  h  o,  after  being  filled  with  water,  are 
inverted  in  the  vessel,  passing  through  holes  in  the 
stopper;  n  and  p  are  platinum  wires  passing 
through  the  sides  of  the  vessel  into  the  open  ends 
of  the  tubes.  When  the  poles  of  the  battery  are 
connected  with  the  wires,  the  positive  with  p,  and 
the  negative  with  n,  hydrogen  gas  is  disengaged 
at  the  negative,  and  oxygen  at  the  positive  wire. 
The  two  gases  will  rise  up  in  the  tubes  in  small  bubbles,  and 
displace  the  water.  By  measuring  the  gases,  it  will  be  found 
that  there  will  be  exactly  two  measures  of  hydrogen  in  the 
tube  h  to  one  of  oxygen  in  the  tube  o.  If  the  gases  are  col- 
lected in  the  same  tube  and  exploded  in  the  eudiometer,  they 
will  entirely  disappear,  and  water  will  again  be  formed.  By 
this  means,  the  composition  of  water,  both  by  analysis  and 
synthesis,  is  accurately  ascertained. 

This  important  discovery  led  to  similar  trials  upon  other 
substances.  Other  compounds,  such  as  acids,  salts,  and  alka- 


Chemical  Effects  of  Galvanism.  87 

lies,  were  subjected  to  the  agency  of  galvanism,  and  all  were 
decomposed  —  one  of  their  elements  appearing  at  the  positive, 
the  other  at  the  negative  pole.  In  these  decompositions,  it 
was  found  that  the  same  kind  of  body  always  went  to  the 
same  pole.  The  metals,  inflammable  substances  in  general, 
alkalies,  earths,  and  the  oxides  of  the  common  metals,  were 
uniformly  found  at  the  negative  wire,  while  oxygen,  chlorine, 
and  the  acids,  were  found  at  the  positive  pole.  This  led  to 
a  division  of  substances  into  Electro-positive,  and  Electro- 
negative—  adistinction,however,  which  is  not  found,  by  later 
experiments,  to  accord  with  facts. 

2.  The  transfer  of  chemical  substances  from  one  vessel  to 
another  was  noticed  by  Sir  II.  Davy.  This  transfer  may  be 
shown  by  two  wine-glasses,  (Fig.  39.) 

Put  a  solution  of  sulphate  of  soda  into  one, 
71,  and  distilled  water  into  the  other,  p ;  then 
connect  them  with  moistened  amianthus  or 
cotton  thread.  If,  now,  the  negative  pole  of 
the  battery  is  connected  with  n,  and  the  pos- 
itive with  p,  the  acid  will  pass  over  into  the  cup  p  containing 
the  distilled  water  —  if  the  poles  are  reversed,  the  alkali  will 
pass  over  into  this  cup.  If,  instead  of  distilled  water,  infusion 
of  purple  cabbage  be  used,  the  presence  of  the  acid  will  be 
detected  by  the  red  color  which  it  will  give  to  the  infusion, 
and  that  of  the  alkali  by  its  changing  the  infusion  to  green.* 

But  the  effect  in  this  experiment,  and  in  those  where  three 
vessels  are  used,  (the  middle  one  of  which,  although  contain- 
ing a  very  delicate  test  of  the  presence  of  an  acid  or  of  an 
alkali,  will  suffer  them  to  pass  through  it  without  detection,) 
can  be  accounted  for  on  the  principle  that  a  part  of  the  salt 
passes  over  into  the  cup  by  capillary  attraction ;  as  it  has 

Fig 

*  A  very  simple  apparatus  for  showing  the  changes  of 
color  when  salts  in  solution  are  subjected  to  galvanic 
action,  is  shown  in  Fig.  40,  which  consists  of  a  glass  tube, 
bent  in  the  form  of  the  letter  U.  Fill  both  legs  with  a 
neutral  salt  colored  with  the  infusion  of  purple  cabbage  ; 
on  immersing  the  poles  p  and  n}  the  color  may  be  trans- 
ferred from  one  leg  to  the  other  as  often  as  the  poles  are 
changed. 


88        Electricity.  —  Chemical  Effects  of  Galvanism. 

been  proved  by  Faraday  that  decomposition  never  takes 
place  unless  the  electric  fluid  actually  passes  through  the  sub- 
stance. 

It  was  in  pursuing  these  researches  that  Davy  made  his 
great  discovery  of  the x  decomposition  of  the  alkalies  and 
earths,  which,  until  that  time,  had  been  considered  simple 
bodies.' 

77ieory.  The  theory  of  decomposition,  proposed  by  Davy, 
was  this :  He  conceived  that  the  poles  of  the  battery  were 
centres  of  attraction  to  one  element  of  the  compound,  and  of 
repulsion  to  the  other ;  hence,  when  the  two  poles  were  im- 
mersed in  water,  the.  oxygen  of  the  water  was  attracted  by 
the  positive,  and  repelled  by  the  negative  pole,  while  the  hy- 
drogen was  repelled  by  the  positive  and  attracted  by  the  neg- 
ative pole.  The  elements,  thus  acted  upon  by  four  forces, 
were  separated,  and  made  to  appear  at  their  respective  poles. 

But  this  theory  does  not  account  for  all  the  phenomena. 
If  it  were  true,  we  should  expect  decomposition  to  be  effected 
by  one  pole  alone,  as  it  exerts  the  attractive  and  repellent 
influence ;  but  this  is  never  the  case. 

Mr.  Faraday  has  lately  revised  this  part  of  the  subject,  and 
not  only,  added  much  that  is  new,  but  shown  that  many  prin- 
ciples, especially  the  above  theory,  are  erroneous. 

He  contends  that  the  poles  have  no  attractive  or  repulsive 
tendency,  but  simply  afford  a  path  for  the  voltaic  currents 
to  enter  the  liquid.  Instead  of  poles,  he  calls  them  elec- 
trodes* which  means  the  way  or  door  for  electric  currents, 
and  may  be  air,  water,  metal,  or  .any  other  substance  ^capable 
of  conducting  the  currents  to  and  from  the  substance  to  be 
decomposed.  The  point  where  the  positive  current  enters 
the  liquid,  he  calls  the  anodej  and  that  where  it  quits  it,  the 
cathode,  f 

When  a  compound  is  decomposed  by  galvanism,  it  is  said 
to  be  electrolyzed,$  and  substances  capable  of  decomposition 
are  called  electrolytes;  the  elements  of  an  electrolyte  are 


*  From  yJLixTQor  and  6$o=;,  a,  icay. 

t  From  ai«,  upwards,  and  o(W,  the  way  in  which  the  sun  rises. 

t  From  xctro,  downwards,  the  way  in  which  the  sun  sets. 

§  From  jjAexrfov  and  xuw,  to  unloose  or  set  free. 


Results  qf  Faraday's  Investigations.  89 

called  ions*  Anions  are  the  ions  which  appear  at  the  anode ; 
cations,  those  that  appear  at  the  cathode.  The  anions  are 
the  electro-negative  substances,  such  as  oxygen,  chlorine, 
acids,  etc. ;  the  cations,  the  electro-positive,  such  as  hydro- 
gen, alkalies,  metals,  etc. 

The  following  are  the  principal  results  of  Faraday's  inves- 
tigations :  — 

1.  All  compounds,  contrary  to  what  has  been  hitherto 
supposed,  are  not  electrolytes ;  that  is,  are  not  directly  de- 
composable by  the  voltaic  currents.     But  many  bodies  may 
be  decomposed  by  secondary  action.     Thus  water  is  directly 
decomposed  by  an  electric^  current ;  but  nitric  acid  is  decom- 
posed by  secondary  action  —  the  decomposition  of  the  water 
contained  in  it,  aids  the  decomposition  of  the  acid.     Very 
numerous  secondary  actions  are  produced  in  this  way,  because 
the  disunited  elements,  separated  by  direct  action,  are  pre- 
sented in  their  nascent  form,  which  is  peculiarly  favorable  to 
chemical  action. 

2.  Most  of  the  salts  or  secondary  compounds  are  resolva- 
ble into  acid  and  oxide ;  but  in  the  binary  compounds,  such 
as  acids  and  oxides,  the  ratio  of  combination  has  an  influence 
which  has  been  hitherto  overlooked.     No  two  elements  ap- 
pear capable  of  forming  more  than  one  electrolyte.     The 
proto-chloride  of  tin  is  readily  decomposed,  but  the  by-chlo- 
ride is  not.     Hence  substances  which  consist  of  a  single 
equivalent  of  one  element,  and  two  or  more  of  another,  are 
not  electrolytes,    that   is,  are   not   decomposed   directly  by 
electricity. 

3.  Most  of  the  simple  substances  are  -ions,  that  is,  capable 
of  forming  compounds  decomposable  by  galvanism. 

4.  -A  single  ion,  by  itself,  has  no  tendency  to  pass  to  either 
of  the  electrodes,  that  is,  it  is  indifferent  to  the  voltaic  cur- 
rents. 

5.  There  is  no  such  thing  as  a  transfer  of  the  ions,  in  the 
sense  supposed  by  Davy.     In  order  that  the  elements  of  water 
should  appear  at  the  two  electrodes,  there  must  be  a  row  of 
particles  between  them. 

6.  The  air,  or  the  surface  of  water,  may  constitute  an  elec- 
trode, as  well  as  metals. 

7.  Electro-chemical  decomposition  cannot  occur  unless  a 
current  of  electricity  actually  passes  through  the  compound ; 

*  From  tov,  going,  neuter  participle  of  the  verb  to  go. 
8* 


90  Theory  of  Electro-Chemical  Decomposition. 

that  is,  the  compound  must  be  a  conductor  of  electricity. 
On  this  principle  many  substances,  by  change  of  state,  resist 
decomposition.  Water  is  easily  decomposed,  but  ice  is  not; 
many  solid  substances,  also,  are  not  electrolytes,  because  they 
are  not  conductors.  CHemical  compounds  differ  in  the 
trical  force  required  for  their  decomposition ;  some  require 
but  a  feeble  current,  others  a  powerful  one. 

8.  The  conduction  of  the  electric  currents  in  the  cells  of  a 
battery  depends  upon  decomposition.     If  the  zinc  or  the  cop- 
per be  attacked  chemically  by  a  substance  which  is  simple,  or 
a  non-conductor,  no  currents  can  be  set  in  motion. 

9.  Electro-chemical    decomposition    is    perfectly   di  finite ; 
that  is,  in  the  voltaic  circle  32.3  parts  of  zinc  are  dissolved 
during  the  evolution  of  one  part  of  hydrogen.     This  is  in  the 
ratio  of  their  chemical  equivalents.     The  same  is  true  of  all 
electrolytes.     Hence  Mr.  Faraday  has  given  to  the  quantities 
of  electricity,  requisite  to  effect  the  decomposition  of  various 
substances,  the  name  of  electro-chemical  equivalents.     This  is 
a  new  and  important  discovery ;  it  seems  to  prove  that  the 
cause   of    chemical    combination   or   affinity   is  eltitridtti. 
Hence,  in  order  to  estimate  the  quantity  of  electricity  circu- 
lating in  a  voltaic  apparatus,  it  is  only  necessary  to  collect  the 
gas  evolved  from  the  acidulated  water  during  any  given  time. 

Theory  of  Electro-Chemical  Decomposition.  We  have  al- 
ready noticed  the  theory  of  Davy,  which  supposes  that  all 
substances  are  in  one  of  .two  states  of  electricity,  and  that  the 
poles  have  an  attractive  and  repulsive  force ;  but  Mr.  Faraday 
has  shown  that  this  theory  cannot  be  true.  All  substnnr* •< 
are  indifferent  when  by  themselves,  but  assume  one  of  the 
two  states  when  brought  in  contact.  Only  one  substance  is 
absolutely  negative  —  oxygen ;  and  but  one  absolutely  posi- 
tive — potassium :  between  these  extremes,  they  may  be  made 
to  assume  either  positive  or  negative  states.  To  account  for 
the  decomposition  of  water,  we  must  conceive  of  a  line  of 
particles  between  the  two  electrodes,  along  which  the  current 
passes.  When  a  particle  of  oxygen  is  evolved  at  the  positive 
electrode,  its  hydrogen  is  not  transferred  at  once  to  the  op- 
posite electrode,  but  unites  with  the  oxygen  of  the  contiguous 
particle  of  water,  on  the  side  towards  which  the  positive 
current  is  moving ;  then  it  passes  to  the  next,  and  so  on,  until 


Magnetic  Effects  of  Electricity.  91 

it  arrives  at  the  pole.  A  similar  row  of  particles  of  oxygen 
start  from  the  negative  electrode  at  the  same  moment,  and 
combine  successively  with,  the  particles  of  hydrogen  as  they 
pass  them  on  their  way  to  the  positive  pole  or  electrode.*  Jjt 
is  supposed  that  other  compounds  are  decomposed  by  a 
similar  process. 

Magnetic  Effects  of  Electricity,  of  Electro-Magnetism.  — 
History.  It  had  been  noticed  for  a  long  time  that,  when  a 
ship,  for  example,  was  struck  with  lightning,  the  magnetic 
needle  often  had  its  poles  destroyed  or  reversed,  and  that  the 
iron  often  became  magnetic.  This  led  to  the  supposition, 
that  electricity  might  be  employed  to  communicate  the  mag- 
netic properties  to  iron  or  steel ;  but  no  results  of  importance 
were  obtained  until  the  winter  of  1819,  when  Prof.  Oersted, 
of  Copenhagen,  made  his  famous  discovery,  which  forms  the 
basis  of  a  new  and  very  important  branch  of  science. 

I.  Influence  of  Voltaic  Currents  upon  the  Magnetic  Nee- 
dle. The  discovery  made  by  Oersted  was,  that  the  me- 
tallic wire,  or  any  part  of  a  closed  voltaic  circle,  causes  a 
magnetic  needle,  when  brought  near  it,  to  deviate  from  its 
natural  position,  and  assume  positions  depending  upon  the 
relative  position  of  the  needle  and  the  wire. 

Thus,  suppose  a  magnetic  needle  freely  suspended  with  its 
poles  pointing  north  and  south.  (See  fig.  41.) 

1.  If,  now,  a  positive  current  pass  from  north  to  south  in 
the  same  plane  with  the  needle,  but  a  little  above  it,  the  north 
pole  will  turn  to  the  east,  and  the  south  pole  to  the  west. 

2.  If  the  current  pass  under  the   needle,  the  north  pole 
moves  west,  and  the  south  east. 

3.  If  the  current  pass  on  the  west  side  of  the  needle,  and 
in  the  same  horizontal  plane,  the  magnet  will  have  a  tendency 
to  move  in  a  vertical  direction,  the  north  pole  being  elevated, 
and  the  south  depressed. 

4.  If  the  current  pass  on  the  east  side,  the  north  pole  is 
depressed,  and  the  south  elevated. 

5.  If  the  current  flow  from  south  to  north,  the  needle  will 
move  in  opposite  directions. 

*  The  quantity  of  electricity  sufficient  to  decompose  a  single  grain 
of  water  would  be  equal  to  a  powerful  flash  of  lightning. 


92  Magnetic  Effects  of  Electricity,  or 

The  deflection  is  rarely  45°,  in  consequence  of  the  mag- 
netism of  the  earth ;  but  if  that  force,  is  counteracted,  as  it 
may  be,  by  suspending  two  magnets  near  each  other,  of  equal 
power,  with  their  poles  reversed,  the  declination  will  be  90° ; 
hence  the  tendency  of  a  magnetic  needle  is  to  stand  at  right 
angles  to  an  electric  current* 

6.  If  the  wire  be  placed  in  a  plane,  perpendicular  to  the 
one  in  which  the  magnet  moves,  and  the  positive  current 
ascends  or  descends  to  the  centre  of  the  needle,  no  action 
will  take  place ;  but  if  it  be  moved  towards  the  north  or  south 
poles,  they  will  be  attracted  or  repelled,     lltncr  the  plane  in 
which  a  needle  moves  is  always  perpendicular  to  that  in  which 
the  voltaic  currents  circulate. 

7.  The   phenomena   of   Electro-Dynamic    action    result 
wholly  from  electricity  in  motion,  and  depend  upon  quan- 
tity alone ;  hence  a  simple  circle  of  large  plates  is  best  fitted 
for  exhibiting  it.* 

From  the  above  facts  it  will  be  seen,  that  the  magnetic 
needle  may  be  employed,  not  only  to  ascertain  the  existence 
and  direction  of  voltaic  currents,  but  also  to  measure  their 
force.  The  instruments  used  for  these  purposes  are  called 

Galvanometers  or  Atu&ipKo't.     As  it  is  proved  by  experi- 
ment that  every  part  of  a  wire  in  a  closed  circuit  exerts  an 
equal  force  upon  the  poles  of  a  needle,  if  we  can  increase 
the  number  of  points,  the  combined  force   will  be  greatly 
increased.     This  can  be  done  by  coiling  the  wire  into  the 
form  of  a  circle  or  rectangle;  each  coil  will  exert  its  own 
force,  independent  of  its  neighbor,  and  the  united  force  will 
depend  upon   the  num- 
ber of  coils.    Thus  (Fig.        '  *T 
41)  NP  are  the  two  ends  ^    £L 
of  a  copper  wire  bent  in  ^T    V  -^  ^  CL 

the  form  of  a  rectangle,     11 

fn  the  centre  of  which,       ^  u'  IT 

and  in  a  plane  perpendio  "  * 

ular  to  the  plane  of  the 
wire,  is  placed  a  mag- 
netic needle.  A  gradu- 
ated circular  plate  meas- 

*  The  simple  battery,  Fig.  35,  p.  80,  is  best  fitted  for  experiments  on 
this  subject.  The  exciting  liquid  should  be  a  solution  of  sulphate  of 
copper. 


"wr    I 

CL» 


Electro-Magnetism. 


93 


ures  the  degree  of  declination,  which  indicates  the  quantity 
of  electricity  circulating  along  the  wires.  It  will  be  seen, 
that  if  the  positive  current  pass  above  the  needle  from  north 
to  south,  that  is,  from  P  to  «,  and  then  pass  around  the  south 
pole  from  A  to  B,  there  will  be  double  the  effect  produced. 
By  increasing  the  number  of  coils,  the  deflection  of  the 
needle  will  be  much  greater.  This  constitutes  the  Electro- 
Magnetic  Multiplier  of  Schweigger. 

If  the  directive  power  of  the  needle  be  destroyed,  or  if  the 
currents  are  sufficiently  powerful,  the  needle  will  stand  at 
right  angles  to  the  direction  of  the  currents.  Then,  if,  at  the 
moment  it  has  attained  this  point,  the  currents  be  sent  in  an 
opposite  direction,  it  will  perform  a  revolution.  Thus,  by 
changing  the  direction  of  the  currents,  a  needle  may  be  made 
to  revolve  rapidly. 

If  the  magnet  is  fixed,  and  the  rectangle  suspended  free  to 
move,  it  will  exhibit  the  same  phenomena  while  the  voltaic 
currents  are  passing  around  it.  '•' 

Fig.  42. 


94  Magnetic  Effects  of  Electricity,  or 

The  Revolving  Rectangle  is  constructed  on  this  principle. 
MM  (Fig.  42)  is  a  permanent  horse-shoe  magnet ;  C,  a  rec- 
tangular coil  of  copper  wire,  connected  at  each  end  to  an 
axis,  by  which  means  it  may  be  made  to  revolve ;  ZP  are  two 
cups,  to  form  a  connection  with  the  poles  of  a  battery ;  the 
wires  bb  are  connected  with  the  cups,  and  press  on  opposite 
sides  of  the  cylindrical  metallic  pole-changer,  which  revolves 
between  them.  The  pole-changer  consists  of  two  pieces  of 
silver,  with  a  small  space  between  them ;  one  of  these  pieces 
is  connected  with  one  end  of  the  wire  of  the  rectangle,  and 
the  other  piece  with  the  other  end ;  a  is  an  arch  of  brass  to 
support  the  rectangle  and  the  wires.  If  the  two  cups  be 
connected  with  the  battery,  P  with  the  positive,  and  '/*  with 
the  negative  pole,  the  positive  current  will  pass  along  the 
wire  b  next  to  N,  and  from  the  wire  to  one  side  of  the  pole- 
changer,  and  thence  several  times  around  the  rectangle  to 
the  wire  b  next  to  S. 

When  the  positive  current  is  passing  from  P  around  this 
rectangle,  one  side  is  impelled  towards  one  pole  of  the  magnet, 
and  the  other  towards  the  other  pole.  When  the  sides  arrive 
in  the  plane  of  the  poles,  the  force  still  continues  to  act,  and 
they  are  forced  by,  and  complete  half  a  revolution,  standing 
again  at  right  angles  to  the  poles  of  the  magnet,  the  point  at 
which  they  commenced  their  revolution:  at  this  point  the 
pole-changer  sends  the  currents  in  opposite  directions,  and 
the  revolution  is  continued.  Reverse  the  current,  by  chang- 
ing the  battery  wires,  and  the  rectangle  will  revolve  in  an 
opposite  direction. 

II.  TJic  influence  of  voltaic  currents  on  soft  iron  and  steel 
was  noticed  by  Davy  and  Arago  about  the  same  time.  If  an 
iron  or  steel  needle  be  suspended  in  the  galvanometer  instead 
of  the  common  needle,  at  right  angles  to  the  conducting 
wires,  permanent  \magnetism  will  be  communicated  to  the 
steel,  and  the  iron  will  become  powerfully  magnetic,  as  long 
as  the  currents  circulate,  but  will  lose  this  property  when 
the  circuit  is  broken.  Davy  succeeded  in-  producing  a  similar 
effect  by  a  discharge  from  a  common  electric  battery. 

1.  This  effect  can  be  exhibited  in  the  most  satisfactory 
manner  by  coiling  an  insulated  copper  wire  in  the  form  of 
a  helix,  d,  (Fig.  43,)  and  connecting  the  two  ends  of  the  wire 
bb  with  the  cups  CZ,  into  which  the  poles  of  a  battery  may 


Electro-Magnetism. 


95 


be  inserted.  Bars  of  soft  iron  or 
steel,  placed  in  the  coil,  will  become 
magnetized  the  instant  the  voltaic  cur- 
rents circulate  around  the  coil.  If 
the  positive  current  flows  from  Z 
around  the  helix,  n  will  be  the  north 
pole,  and  s  the  south  pole.  If  it  flow 
from  C,  the  poles  will  be  reversed. 

2.  If  a  bar  of  soft  iron  (Fig.  44) 
be  wound  with  copper  wire  from  c  to 
a  in  one  direction,  and  from  a  to  c?  in 
an  opposite  direction,  and  currents  of 
electricity  passed  around  the  bar,  by 
connecting   the  wires  b   e 

with  a  voltaic  battery,  the 
bar  will  have  three  poles ;  c 
and  d  will  be  similar  poles, 
and  a  an  opposite  pole  com- 
mon to  the  other  two,  as 
may  be  shown  by  bringing  a 
magnetic  needle  near  each. 
By  changing  the  direction 
of  the  battery  currents,  the 
poles  are  reversed;  hence 
the  kind  of  pole  depends  upon  the 
direction  of  the  voltaic  currents. 

3.  Although  soft  iron  does  not  re- 
tain its    magnetism,   yet    its  magnetic 
properties,  while  the  voltaic  currents 
are  passing  around  it,    are   truly  sur- 
prising. 

If  a  soft  iron  cylinder,  two  inches  in 
diameter,  and  bent  in  the  form  of  a 
horse-shoe  magnet  D,  (Fig.  45,)  be 
wound  with  copper  wire,  and  the  ends 
BC  connected  with  the  battery,  it  will 
be  converted  into  a  powerful  magnet. 
On  applying  the  armature  A,  it  will 
sustain  several  hundred  pounds.  Mag- 
nets of  this  description  may  be  made 
to  sustain  from  200  to  2000  Ibs.  It 
will  be  seen  that  the  principle  is  the 
same  as  in  the  helix ;  and,  as  in  the  mul- 


.  43. 


Fig.  44, 


Fig.  45. 


96 


Magic    Circle. 


tiplier,  by  increasing  the  number  of  coils,  the  magnet  becomes 
more  powerful,  but  the  force  does  not  increase  directly  as  the 
number  of  coils;  for  each  additional  coil  is  farther  from  the 
axis  of  the  iron  bar,  and  the  power  it  exerts  is  inversely  as 
the  square  of  the  distance  from  the  axis. 

4.  The  Magic  Circle,  with  two  iron  ar- 
matures,  acts  also  on  the  same  principle. 

r  (Fig.  46)  is  a  coil  of  insulated  copper 
wire  ;  ab  the  two  ends  which  may  be  con- 
nected with  the  battery.  When  the  wires 
b  a  are  connected  with  the  battery,  and  the 
two  armatures  are  brought  into  contact,  one 
of  them  passing  through  the  ring,  they  adhere 
to  each  other  very  strongly,  and,  although 
they  weigh  less  than  J  lb.,  they  will  sustain  a  weight  of  56  Ibs. 
without  separation.  The  voltaic  currents  not  only  communi- 
cate magnetism  to  the  iron  and  steel  placed  in  the  ring,  but 
the  helix  itself  becomes  magnetic  while  transmitting  the  cur- 
rents, as  is  proved  by  its  attracting  iron  filings.  These  ,m<! 
other  facts,  developed  by  voltaic  currents,  seem  to  prove  the 
identity  of  the  magnetic  and  electric  fluids. 

5.  Vibrating  Magic  Circle.     MM  (Fig.  47)  is  an  elcdrn- 
magnct,  which  may  be  used  instead  of  a  permanent  magnet  ; 
c,  a  coil  of  coarse  wire  suspended  from  the  post  S  ;  one  end  of 
the  wire  a  dips  into  the  cup  e  ,  which  is  connected  with  the  post 
S,  and  which  also  communicates  with  p;  the  other  end  of  tin- 
wire  d  is  connected  with  the  other  cup, 

from  the  post  S, 
and  into  which 
also  one  of  the 
poles  of  the 
battery  may  be 
immersed;  con- 
nect the  other 
pole  of  the  bat- 
tery with  p,  and 
a  current  of 
electricity  will 
pass  along  the 
post  S  to  the 
cup  e;  as  the 
wire  a  dips  into 
it,  the  current 


which  is  insulated 


Volta-Electric  Induction. 


97 


will  pass  down  the  wire  b  around  the  coil  c,  and  then  up  the 
wire  d  to  the  other  cup;  as  the  currents  circulate,  the  coil 
will  be  attracted  to  the  pole  of  the  magnet  M ;  this  will  lift  a, 
and  break  the  circuit,  and  the  coil  will  fall  back  beside  the 
post  S ;  a  will  again  be  immersed  in  e,  and  the  coil  be  again 
attracted  upon  M.  Thus  vibrations  are  produced  as  long  as 
the  currents  of  electricity  circulate. 

III.  Volta-Electric  Induction.  The  fact  that  an  electri- 
cally-excited body  induced  electricity  in  other  bodies  brought 
near  it,  (page  75,)  led  Faraday  to  inquire  whether  electricity 
in  motion  would  not  have  the  same  effect.  This  fact  he  soon 
established. 

If.  a  copper  wire  be  wound  in  the  form  of  a  helix,  and  the 
ends  connected  with  a  battery,  and  then  another  wire  be 
wound  around  this,  but  insulated  from  it,  and  the  ends  con- 
nected with  a  galvanometer,  currents  of  electricity  will  be 
induced  in  the  insulated  wire,  as  often  as  the  battery  current 
is  broken.  All  the  effects  of  galvanism  may  be  produced  by 
the  insulated  wire. 

The  phenomena  of  Volta-Electric  Induction  mayjae  ex- 
hibited in  the  most  satisfactory  manner  by  the 

Fisr.  48. 


9 


98 


Volta-Electric  Induction. 


Separable  Helices,  (Fig.  48,)  an  apparatus  very  well  fitted 
for  illustration,  for  producing  sparks,  and  imparting  shocks 
of  almost  any  degree  of  intensity. 

6  (Fig.  48)  is  a  hollow  coil  of  coarse  wire  fixed  upon  a 
stand,  Z  ;  one  end  of  the  wire  is  connected  with  the  cup,  and 
the  other  with  the  steel  break-piece*  which  is  fixed  to  the 
stand,  by  the  side  of  the  coil  ;  a  is  a  coil  of  fine  wire,  which 
may  be  placed  over  the  coil  b  ;  d  is  a  bundle  of  wires,  which 
may  be  slipped  into  the  copper  case  c,  and  placed  in  the 
centre  of  the  coil  b. 


Fig.  49. 


Fig.  49  represents  this  apparatus  entire.  The  following 
are  the  principal  facts  which  it  is  fitted  to  exhibit  :  — 

Exp.  Connect  one  pole  of  the  battery  with  the  cup  on  the  left  of  c, 
(Fitr.  48,)  and  move  the  other  pole  along  the  break-piece;  vivid  sparks 
willbe  produced  at  each  interruption. 

Exp.  Remove  from  the  wires  d  the  copper  case  c,  and  insert  them 
gradually  in  the  coil  b  while  the  currents  are  circulating,  and  the 
sparks  on  the  break-piece  will  increase  in  brilliancy  until  the  wires 
reach  the  bottom,  when  the  greatest  effect  will  be  produced. 


*  A  break  may  consist  of  air,  or  any  non-conductor,  so   connected 
with  a  conductor,  that,  when  ,the  wire  conveying  the  voltaic    current 

E  asses  from  the  conductor  to  the  non-conductor,  the    circuit  may  be 
roken  ;  and  it  is  only  at  the  moment  of  interrupting  the  battery  current 
in  the  inner,  that  electricity  is  induced  in  the  outer  coil. 


Magneto-Electric  Induction. 


99 


Exp.  Place  the  coil  a  upon  i,and  let  the  currents  circulate  as  before. 
If  the  handles  e  /,  (Fig.  4!),)  which  communicate  with  the  extremities 
of  the  wire  forming  the  coil  a,  be  held  in  the  hands,  powerful  shocks 
will  be  felt  as  the  wire  conveying  the  battery  cmrent  passes  across  the 
break-piece.  As  the  outer  is  insulated  from  the  inner  coil,  the  shocks 
do  not  proceed  from  the  battery  current,  but  from  currents  induced  in 
the  wire  of  the  outer  helix.  Currents  thus  induced  produce  all  the 
phenomena  of  the  battery  currents. 

Exp.  A  single  wire*  will  increase  the  power  of  the  shocks,  and  by 
increasing  the  number  of  wires,  the  sparks  will  increase  in  brilliancy, 
and  the  shocks  will  become  more  and  more  powerful. 

Exp.  If  the  copper  case  be  placed  upon  the  wires,  the  effect  will  be 
the  same  as  when  no  wires  are  used. 

IV.  Magneto-Electric  Induction.  The  power  of  the 
magnet  to  induce  electricity  greatly  exceeds  that  of  vol- 
taic currents. 

Fig.  50. 


The  apparatus  best  fitted  to  exhibit  this  effect  is  the  Mag- 
neto-Electric Machine,  (Fig.  50,)  which  consists  of  a  perma- 
nent horse-shoe  magnet,  SN,  supported  by  pillars  upon  the 
stand  Z,  and  an  armature,  g,  wound  with  copper  wire,  and 
made  to  revolve  upon  an  axis,  c,  near  the  poles  of  the  magnet, 
by  means  of  the  wheel  li;  one  end  of  the  wire  is  soldered  to 
the  axis,  by  which  means  it  js  connected  with  a  break-piece, 
against  which  the  wire  e  presses ; '  the  other  end  of  the  wire 

*  Fine  wires  answer  a  better  purpose  than  a  solid  bar  ;  if,  however, 
the  bar  be  slit  lengthwise  down  to  the  axis,  the  effect  will  be  nearly 
equal  to  the  wires,  and  if  the  copper  case  be  sawed  open  lengthwise, 
it  will  not  destroy  the  effect  of  the  wires. 


100  Theory  of  Elcctro-Magmtismy  etc. 

is  soldered  to  a  silver  ferule,  a,  insulated  from  the  axis,  against 
which  the  wire  b  presses;  the  wires  c  b  communicate  with 
the  cup  into  which  the  wire  p  is  inserted ;  the  wire  n  is  con- 
nected with  the  axis  by  means  of  the  post  oil  the  right  of  b ; 
p  and  n  therefore  represent  the  two  ends  of  the  wire  which 
surrounds  the  armature.  When  the  armature  is  set  in  motion 
by  the  multiplying-wheel  A,  its  magnetic  state  is  continually 
changing.  When  the  two  extremities  of  the  armature  are 
midway  between  the  poles  of  the  magnet,  the  armature  is 
neutral.  As  they  advance  towards  the  poles,  they  acquire  a 
gradually-increasing  polarity,  until  they  are  opposite  the  poles, 
and  gradually  diminish,  as  they  pass  the  poles,  until  they  are 
midway  again  between  the  poles,  when  the  armature  becomes 
neutral,  as  before.  By  this  revolution,  a  current  of  elec- 
tricity will  be  induced  in  the  wire  which  surrounds  the  arma- 
ture, and  will  pass  from  the  break-piece  to  the  ferule,  by 
means  of  the  wire  e  6,  which  connects  them;  excepting, 
when  the  end  of  the  wire  e  is  passing  across  the  break-piece, 
then  there  will  be  induced  in  the  wire  which  surrounds  the 
armature  a  secondary  current,  which  passes  by  sparks  at  each 
point  of  interruption,  or  at  the  wires  p~n,  if  they  are  brought 
nearly  into  contact.  By  pressing  the  hands,  previously  moist- 
ened, upon  the  handles  connected  withp  n,  powerful  shocks 
will  be  felt  at  each  interruption.  Deflagrations  may  also  be 
produced,  and  decompositions  effected,  and  generally  the 
electricity  thus  induced  produces  effects  precisely  similar  to 
those  from  the  voltaic  battery.  The  phenomena  of  elec- 
tricity, thus  p/oduced,  are  sometimes  called  Magncto-Elcc- 
tr'uity* 

V.  Theory  of  Electro-Magnetism  andMagneto-Electr'uiti/. 
In  order  to  understand  the  theory  of  M.  Ampere,  by  which 
the  phenomena  of  electro-magnetism  and  magneto-electricity 
may  be  best  explained,  it  is  only  necessary  to  keep  in  view 
the  following  principle,  which  lies  at  the  basis  of  the  theory : 

When  two  positive  or  two  negative  currents  arc  passing  in 
the  same  direction,  and  parallel,  thc.y  attract,  and  when  pass- 
ing in  opposite  directions,  they  repel  each  other. 


*  The  best  apparatus  for  experiments  upon  electro-magnetism  and 
magneto-electricity,  is  manufactured  by  Daniel  Davis,  Jr.  No.  11, 
Cornhill,  Boston. 


Theory  of  Electro-Magnetism,  etc. 


10] 


If,  now,  we  suppose  that  all  magnetic  bodies,  and  the  earth 
itself  among  the  number,  derive  their  magnetic  properties 
from  currents  of  electricity  circulating,  in  reference  to  their 
axis,  in  one  uniform  direction  of  revolution,  we  can  account 
for  all  the  phenomena  of  Magnetism,  Electro-Magnetism,  and 

Magneto-Electricity. 

Fig.  51. 

To  make  this  view  clear.  Suppose  that 
around  the  cylinder  of  Ueel,  (Fig.  51,)  at  right 
angles  to  the  axis,  currents  of  positive  electricity 
are  constantly  circulating  in  a  direction  opposite 
to  that  in  which  the  sun  moves.  The  cylinder 
\vilL  be  a  magnet,  n  the  north  pole,  and  S  the 
south  pole,  and,  if  it  be  poised  upon  a  pivot,  it 
will  differ  in  nothing  but.  in  form  from  a  mag- 
netic needle. 

Application  of  the   Theory.     1.    The  reason 
tnat   the   needle   turns   to   the   east    when   the 
positive  current  passes    above    it  from  north  to 
south  is,  that  the  currents  in  the  magnet,  and  those  in  the 
wire,  move  in  different  directions.     The  needle  is  repelled, 
and  turns  so  that  the  currents  may  coincide. 

2.  When  the  positive  current  passes  under  the  needle,  it 
moves  to  the  west,  because  then  also  the  two  positive  currents 
coincide. 

3.  When  it  passes  on  either  side  in  the  same  horizontal 
plane,  it  tends  to  a  vertical  motion,  for  the  same  reason  as 
above ;  but  if  the  positive  current  passes  from  south  to  north, 
the  phenomena  are  all  reversed. 

4.  When  it  passes  around  the  poles  in  a  vertical  plane,  in 
the  same  direction  in  which  the  sun  appears  to  move,  the 
needle  will  perform  one  half  a  revolution,  because  the  cur- 
rents move  in  opposite  directions,  and  the  needle  revolves  so 
that  the  currents  in  it  may  coincide  with  those  in  the  con- 
ducting wire. 

5.  Bars  of  steel  and  soft  iron   become   maonctic    when 

O 

placed  in  the   helix   around   which   currents   of  electricity 
circulate,  because  similar  currents  are  induced  m  them. 

Q* 


102  Thermo-Electricity. 

6.  If  we  suppose  positive  currents  of  electricity  to  be 
passing  around  the  earth  in  the  same  direction  in  which  the 
sun  appears  to  move,  they  would  convert  it  into  a  magnet, 
the  north  pole  of  the  earth  corresponding  to  the  south  pole  of 
the  magnetic  needle ;  hence,  if  soft  iron  or  steel  bars  are  placed 
in  a  north  and  south  direction,  they  will  become  magnets  !>v 
induction,  the  positive  currents  passing  from  west  to  east, 
because  then  they  would  coincide  with  the  same  currents  in 
the  earth  which  pass  from  east  to  west;  hence  the  reason 
that  a  magnetic  needle  stands  north  and  south,  is,  that  the 
currents  of  electricity  circulating  around  the  earth,  and  those 
circulating  in  the  needle,  will  coincide  only  when  the  needle 
takes  that  direction. 

VI.  Thcrmo-Electricity.     Thermo-electric  phenomena  re- 
sult from  currents  of  electricity  excited  in  metals  by  heat. 
The  existence  of  these   currents  was  first  demonstrated   in 
1821  by  Seebeck. 

If  a  magnet  be  suspended  in  a  rectangle  formed  of  a  bar 
of  antimony  or  bismuth,  having  its  extremities  connected 
with  copper  wires, -and  heat  applied  to  one  end  of  the  bar, 
the  needle  will  be  deflected  in  one  direction,  and  in  an 
opposite  direction  when  heat  is  applied  to  the  other  end. 
Similar  effects  are  produced  when  either  end  is  cooled  below 
the  natural  temperature.  Other  metals,  treated  in  the  same 
manner,  exhibit  similar  phenomena,  but  bismuth  and  a»i- 
timony  are  the  best.  Prof.  Gumming  has  shown  that  a 
rotary  motion  may  be  produced  by  placing  platinum  and 
silver  wires,  soldered  together  in  a  circular  form,  upon  a 
magnet,  and  applying  heat. 

VII.  Nature  of  Electricity.     Some  suppose  that  there  is 
no  transfer  of  any  thing  in  what  are  called  electric  currents, 
but  a  process  of  induction  passing  progressively  along  among 
the  molecules  of  a  conductor.     Others  ascribe  them  to  waves 
of  vibrating  matter,   just   as   the  phenomena   of  light    and 
caloric  are  explained,  by  the  undulatory  theory. 

VIII.  Uses  of  Electricity.     1.    Both  voltaic  and  common 
electricity  have  been  employed  in  medicine ;  in  some  cases, 
with  highly  beneficial  effects.     It  acts  powerfully  upon  the 


Electro-Magnetic  Telegraph.  103 

nervous  system,  and  has  been  the  means  of  restoring  sen- 
sation to  parts  of  the  body  which  had  become  paralytic ; 
so  powerfully  does  it  act  upon  the  vital  energies,  that  persons 
who  have  been  deprived  of  life,  either  by  some  accident,  or 
by  design,  have  been  resuscitated  by  its  agency.  Its  influ- 
ence is  constant  and  universal  in  the  animal,  vegetable,  and 
mineral  kingdoms. 

2.  Attempts  have  been  made  to  employ  voltaic  electricity 
as   a  motive  power  in  the    arts,   to   supersede  the  use   of 
steam  ;  but  all  attempts  hitherto  have  been  unsuccessful.    Suf- 
ficient power  has  been  generated  to  turn  a  small  lathe ;  and  it 
is  to  be  hoped  that  an  apparatus  will  yet  be  constructed  to 
render  available  the  great  force  which  this  agent  is  capable 
of  exerting.     This  force  depends  upon  the  property  of  the 
voltaic   currents   to    communicate    magnetism  to   soft  iron, 
thus  producing  a  powerful  attraction,  arid  the  property  of  the 
iron  to  change  its  poles,  and  consequently  its  attracting  and 
repel  liner  power  as  currents  circulate  in  different  directions. 
(See  Fig.  42.) 

3.  Electro-Magnetic    Telegraph.     A    most  beautiful  and 
useful  application  of  voltaic  electricity,  to  communicate  in- 
telligence from  one  place  to  another,  has  lately  been  made, 
in  the  Electro-Magnetic  Telegraph.     Two  stations  are  taken 
fit  some  distance  apart;  at  one  of  the  stations  is  the  battery, 
with  wires  extending  to  the  other  station,  and  connected  with 
a  magnetic  needle  in  such  a  way  that,  when  the  wires  are 
attached  to  the  battery,  a  motion  is  produced  in  the  needle, 
to  which  is    attached  a  pencil,  to  mark  certain  characters 
which  are  agreed  upon  as  symbols  of  ideas. 

The  wires  at  the  second  station  may  be  connected  with  an 
electro-magnet,  upon  the  poles  of  which  an  armature,  having  a 
letter  or  word,  may  be  attracted  the  moment  the  currents  circu- 
late. In  this  case,  there  must  be  as  many  electro-magnets  as 
there  are  letters  employed.  The  experimenter  at  the  first  sta- 
tion inserts  the  wires  a,  for  example,  in  the  battery,  and  the 
observer  at  the  second  station  sees  the  armature  move  upon  the 
poles  of  the  electro-magnet,  raising  the  letter  a ;  the  wires  con- 
nected with  the  letter  b  (or  any  other  letter)  are  then  inserted, 
and  b  rises.  In  this  way  any  word  may  be  spelled.  A  pencil 
may  be  attached  to  the  armatures,  to  mark  in  a  line  all  the  a's, 
and  in  another  line  all  the  6's,  and  so  of  all  the  other  letters ; 
hence  the  words  may  be  written  down  so  as  to  be  easily  read. 
Intelligence  may  thus  be  communicated  to  any  distance  that 
is  desired  with  the  rapidity  of  lightning. 


104 


Electricity.  —  Elcctrography : 


4.  Electrography.  A  still  more  recent  application  of 
voltaic  electricity  has  been  made  to  the  "  production  of 
perfect  metallic  casts  or  copies  of  medals,  copperplates,  and 
other  works  of  art."  The  discovery  appears  to  have  been 
made  about  the  same  time,  by  Prof.  Jacobi,  of  St.  Petersburg, 
and  Mr.  Spencer,  of  Liverpool.  The  instrument  by  which 
this  effect  is  produced  is  the 

Electrotype ;  and  the  effect  depends  upon  the  decomposition 
of  some  metallic  salt,  by  which  the  metal  is  precipitated  upon 
the  object  to  be  copied,  either  forming  a  mould  for  the  cast, 
or  raising  lines  which  may  be  used  for  making  impressions 
on  paper  or  other  materials.* 

Fig.  52  represents  one  form  of  the 
electrotype,  and  the  mode  of  taking 
impressions.  A  is  a  glass  vessel,  in 
which  a  division  is  made  by  casting 
across  it  plaster  of  Paris,  (earthen 
ware,  a  bladder,  or  any  porous  mem-  . 
brane,  as  thick  pasteboard,  will  answer 
the  same  purpose.)  Into  one  of  the 
partitions  is  put  a  saturated  solution 
of  sulphate  of  copper,  and  into  the 
other  acidulated  water.  The  object 
C  to  be  copied  is  soldered  to  one  end  of  a  wire,  r/,  and  a 
piece  of  zinc,  Z,  to  the  other  end ;  the  object  is  then  iinmci >* -d 
in  the  cupreous  solution,  and  the  zinc  into  the  acidulated 
water.  The  deposit  of  metallic  copper  then  commences 
upon  the  object  c,  copying,  with  the  most  scrupulous  exact- 
ness, every  line,  and  even  the  shades  of  polish.  In  about 
two  or  three  days,  a  complete  mould  may  be  obtained. 
The  copper  mould  is  separated  from  the  matrix  by  gentle 
heat. 

Theory.  The  metallic  salt  and  the  water  are  both  decomposed.  The 
sulphate  of  copper  is  resolved  into  sulphuric  acid  and  oxide  of  copper, 
the  water  into  oxygen  and  hydrogen.  The  acid  and  oxygen  go  to  the 
zinc,  and  the  hydrogen  and  the  oxide  of  copper  to  the  copper  pole,  the 
hydrogen  unites  with  the  oxygen  of  the  oxide  of  copper,  and  the  me- 
tallic copper  is  deposited  upon  the  metal  or  object  to  be  copied. 


*  For  a  description  of  this  process,  see  Journal  of  Science,  Vol. 
No.  1 ;  also,  Part  IV.  of  Griffin's  Scientific  Miscellany. 


PART    II. 

CHEMICAL    AFFINITY 


I\  all  those  phenomena,  which  appropriately  come  under 
the  observation  of  the  chemist,  chemical  affinity  is  the  great 
cause  to  which  they  are  referred.  Other  agents,  as  light, 
heat,  electricity,  cohesion,  etc.,  modify  its  action,  and  some 
knowledge  of  them  is  therefore  an  essential  preparation  for 
the  study  of  this,  —  the  great  subject  of  chemistry.  The  de- 
tails, to  which  we  shall  attend  in  the  examination  of  particu- 
lar substances,  are,  almost  exclusively,  but  the  effects  of  this 
principle.  The  student,  therefore,  should  be  familiar  with 
the  circumstances  which  modify  its  action,  its  varieties  or 
different  modes  of  operation,  its  effects,  and  especially  the 
laws  in  accordance  with  which  these  effects  are  produced. 

Chemical  Affinity  is  an  attraction,  which  acts  only  at  in- 
.<•  ntiblc  distances,  between  particles  of  different  kinds*  Co- 
hesion is  distinguished  from  it,  by  acting  only  between  par- 
ticles of  the  same  kind,  as  well  as  by  being  governed  by  dif- 
ferent laws. 

Varieties  of  Chemical  Affinity. 

Although  this  power  is  the  same  in  all  cases,  it  will  facili- 
tate the  progress  of  the  student  to  distinguish  some  of  the 

*  A  late  writer  (Griffin,  Chemical  Recreations)  maintains  that  there 
is  no  such  thing  as  chemical  affinity,  because  we  know  merely  that 
bodies  combine.  We  might  as^well  deny  that  any  force  or  power  ex- 
ists because  we  see  only  its  effects.  From  the  fact  that  bodies  do  corn- 
bine,  we  infer  that  some  power  causes  them  to  combine,  although, 
indeed,  we  know  nothing  of  it,  except  in  its  effects. 


X 

106  Varieties  of  Chemical  Affinity. 

different  cases  in  which  it  operates.  Between  many  sub- 
stances it  does  not  exist  at  all,  as  is  seen  in  mixing  oil  and 
water.  The  most  simple  case  is  the  direct  union  of  two  sub- 
stances, as  when  oxygen  gas  and  iron  unite,  and  form  iron 
rust.  This  is  called  Simple  Affinity.  The  combination  of 
alcohol  with  camphor  is  another  example. 

Exp.  But  if  water  be  added  to  this  solution  of  camphor,  the  alcohol 
will  combine  with  the  water,  and  desert  the  camphor,  which  again  ap- 
pears free,  or  is  technically  said  to  be  precipitated.  As  the  alcohol 
appears  to  choose  the  water  in  preference  to  camphor,  such  cases  are 
called  examples  of  single  elective  ujfinity* 

The  following  are  examples  of  the  same  kind  :  — 
Exp.   Into  a  solution  of  sulphate  of  copper  (blue  vitriol)  immerse  a 
dean  iron  wire;  the  sulphuric  acid  (oil  of  vitriol)  will  elect  the  iron, 
and  the  copper  will  be  precipitated,  forming  a  metallic  coating  upon 
the  wire. 

Exp.  Into  a  solution  of  protonitrate  of  mercury  put  a  sheet  of  cop- 
per, or  cents,  well  cleaned  with  dilute  sulphuric  acid ;  the  nitric  acid 
will  elect  the  copper,  and  the  metallic  mercury  will  be.  precipitated, 
and  form  a  covering  over  the  cents,  which  will  give  them  the  appear- 
ance of  silver. 

But,  in  other  cases,  two  compounds  mutually  decompose 
each  other,  and  form  two  new  compounds. 

EXT).  Thus,  if  carbonate  of  ammonia  and  hydrochlorate  of  lime  be 
mingled,  each  will  be  decomposed.  The  former  consisting  of  carbonic 
acid  and  ammonia,  and  the  latter  of  hydrochloric  acid  and  lime,  tfie 
carbonic  acid  will  unite  with  the  lime,  and  the  hydrochloric  acid  with 
the  ammonia,  forming  carbonate  of  lime,  and  hydrochlorate  of  ammo- 
nia. This  change  may  be  very  easily  understood  from  the  annexed 
formula,  in  which  the  symbols  are  used.t 

C     +     Am.  ' 

C  abandons  Am.  and  goes  to  Ca;  at  the 
same  time  HC1  abandons  Ca,  and  goes  to  Am. ;  • 

and  the  results  are  C  +  Ca.  and  HC1  -f-  Am. 

HC1   +     Ca. 

*  Elective  djfinity  is  the  basis  of  chemical  science  ;  for  if  each  sub- 
stance attracted  every  other  with  the  same  force;  when  combination 
had  once  been  effected,  the  decomposition  of  many,  if  not  of  most 
substances,  would  be  impossible;  h^hce  there  would  be  but  few 
changes  in  matter  which  would  come  under  the  investigation  of  the 
chemist. 

t  C=  Carbonic  acid,  and  Am.  =  Ammonia;  HC1  =  Hydrochloric 
acid,  and  Ca.  =  Lime. 


Operation  of  Chemical  Affinity.  107 

Exp.  To  a  solution  of  alum  (sulphate  of  alumina  and  potassa)  add 
a  solution  of  acetate  of  lead.  Sulphate  of  lead  and  acetate  of  alumina 
are  formed  by  a  double  decomposition.  The  sulphate  of  lead  will  be 
precipitated,  and  the  acetate  of  alumina  will  remain  in  solution. 

Exp.  Nitrate  of  ammonia  and  sulphate  of  soda  will  mutually  decom- 
pose each  other.  In  all  cases  of  double  decomposition,  the  alkali  in  one 
of  the  compounds  will  just  neutralize  the  acid  in  the  other,  so  that,  if 
any  delicate  test  of  an  acid  or  an  alkali  (as  vegetable  infusion)  be 
placed  in  the  mixture,  no  effect  will  be  produced  upon  it ;  hence,  as 
the  quantities  of  acid  and  of  alkali,  in  all  neutral  salts,  are  just  suffi- 
cient to  saturate  each  other  when  double  decomposition  takes  place, 
these  quantities  are  called  equivalents. 

Such  cases  are  examples  of  double  elective  affinity*  Cases 
are  more  numerous,  however,  in  which  the  changes  are  much 
more  complicated ;  but  they  may  all  be  referred  to  the  three 
modes  stated  above. 

Circumstances  which  modify  the  Operation  of  Chemical 
Affinity. 

That  one  substance  has  a  stronger  affinity  for  some  than 
for  others,  cannot  be  doubted.  But  combination  and  decom- 
position do  not  always  depend  upon  the  relative  force  of  af- 
finity alone.  Several  circumstances  modify  the  operation 
of  this  power.  These  are,  cohesion,  elasticity,  quantity  of 
matter,  gravity,  and  the  imponderable  agents. 

I.  Cohesion.  In  order  that  substances  should  combine 
with  each  other,  it  is  necessary  that  their  particles  should  be 
in  contact.  But  cohesion  holds  together  the  particles  of  each 
substance,  so  that  they  cannot  be  freely  intermingled.  Co- 
hesion must,  therefore,  be  destroyed  to  facilitate  chemical 
action.  This  may  be  effected  in  three  ways :  — 

1 .    By  reducing  the  substance  to  powder. 

Exp.  Take  two  pieces  of  crystallized  nitrate  of  copper ;  roll  one  of 
them  up  in  tin  foil ;  grind  the  other  to  powder,  and  wrap  it  in  a  piece 
of  the  same  metal;  drop  a  little  water  upon  both  as  they  are  rolled 
up.  In  a  few  minutes,  that  which  is  pulverized  will  combine  with 
the  metal,  and  burst  into  a  flame,  while  the  other  will  not  be  affected. 

Exp.   Take  two  equal  portions  of  chalk,  and  pulverize  one  ;  pour 

*  Single  and  double  elective  affinity  are  the  same  in  principle.  The 
only  difference  is,  that,  in  the  one  case,  a  compound  is  decomposed  by 
a  third  substance,  and  but  two  affinities  are  in  operation,  while,  in  the 
other,  two  compounds  mutually  decompose  each  other,  arid  four  affin- 
ities are  brought  into  action. 


108  Operation  of  Chemical  Affinity. 

dilute  sulphuric  acid  on  each,  and  the  action  will  be  rapid  in  the  case 
of  the  pulverized  chalk,  but  moderate  in  the  other  case.  In  this  ex- 
periment, one  of  the  substances  is  in  solution ;  and  usually  it  will  be 
found  insufficient  to  pulverize  botli  substances,  and  resort  must  be  had 
to  the  second  method. 

2.   By  dissolving  the  body  in  some  liquid. 

Exp.  Mix  together  tartaric  acid  and  carbonate  of  soda;  no  action 
will  follow;  pour  on  water,  and  they  will  be  dissolved,  and  a  violent 
action  ensue. 

Solution  is  effected  when  a  solid  is  put  into  a  liquid,  and 
entirely  disappears,  leaving  the  liquor  clear.  The  body 
which  thus  disappears  is  said  to  be  soluble ;  the  liquid  is 
called  a  solvent,  and  the  compound  liquor  a  solution.  Water 
is  the  principal  solvent;  alcohol,  ether,  oils,  alkalies,  and 
acids,  are  also  employed.  When  water,  or  any  solvent,  has 
dissolved  as  much  of  any  substance  as  it  can,  it  is  said  to  be 
saturated,  and  the  solution  is  called  a  saturated  solution. 

Solution  should  not  be  confounded  with  diffusion,  which 
is  merely  a  mechanical  mixture. 

Exp.  This  distinction  may  be  seen  by  mixing  magnesia  in  water. 
The  particles  of  magnesia  are  suspended  at  first  in  the  water,  rendrr'mrr 
it  turbid,  and  they  would  soon  subside  to  the  bottom  ;  but  if  nitric  acid  be 
added,  the  magnesia  will  be  dissolved,  and  the  water  will  become  clear. 

Most  substances  are  more  soluble  in  hot  than  in  cold 
water;  as  a  hot  saturated  solution  cools,  the  water  will  not 
therefore  be  able  to  hold  in  solution  all  of  the  sul>st;:m-<' 
which  had  been  dissolved,  and  it  appears  again  in  a  solid 
state.  The  power  of  cohesion  has  the  ascendency  over  the 
affinity  of  the  liquid  for  the  solid,  and  forms  the  hitter  into 
crystals.  Hence  the  phenomena  of  crystallization  are  owini: 
to  the  ascendency  of  cohesion  over  affinity. 

By  evaporation,  also,  the  solid  may  be  recovered  from  so- 
lution. In  either  case,  the  crystallization  is  often  confused, 
especially  when  the  process  is  rapid. 

Insolubility  has  been  found'to  exert  a  remarkable  influence 
on  affinity,  in  the  case  of  an  alkali  with  two  acids,  or  an  acid 
with  two  alkalies,  one  of  which  will  form  with  the  alkali  a 
soluble,  and  the  other  an  insoluble  compound.  The  one 
which  is  insoluble  is  always  formed  in  preference  to  the  solu- 
ble compound. 

Exp.  Thus,  if  nitric  and  sulphuric  acids  and  baryta  be  thrown  to- 
gether in  water,  sulphate  of  baryta,  which  is  insoluble,  will  be  formed 
in  preference  to  nitrate  of  baryta,  which  is  soluble. 

It  is  obvious  that,  while  the  solution  of  one  of  the  substances 


Operation  of  Chemical  Affinity.  109 

is  usually  necessary,  the  solution  of  both  will  further  facilitate 
the  action. 

3.  By  heat.  —  Fusion  is  there  duction  of  a  solid  to  a  liquid 
state  by  caloric,  and  facilitates  chemical  action  by  enabling 
the  particles  to  intermingle,  and  come  within  the  sphere  of 
each  other's  affinity.  In  liquids  a  slight  degree  of  cohesion 
remains,  and  hence  heat  is  applied  to  them  with  advantage. 
A  hot  liquid  will  act  more  powerfully  upon  most  solids  than 
the  same  liquid  when  cold. 

II.  Elasticity.      Cohesion,    as   we    have    seen,    opposes 
chemical  action  by  keeping  the  particles  out  of  the  sphere 
of  each  other's  influence.     Elasticity,  or  the  gaseous  state, 
is  still  more  unfavorable  to  the  operation  of  affinity,  because 
the  particles  are  removed  too  far  from  each  other  to  be  at- 
tracted ;  hence  most  gases,  though  possessing  a  strong  attrac- 
tion for  each  other,  will  not  combine  unless  they  are  in  the 
nascent  state,  that  is,  when  in  the  act  of  assuming  the  gase- 
ous form. 

In  this  way  elasticity  not  only  prevents  chemical  union, 
but  it  favors  decomposition. 

1.  When   two   highly-elastic   gases   combine,   forming  a 
liquid  or  solid,  the  compound  will  be  decomposed -by  a  very 
slight  cause :  the  chloride  of  nitrogen  is  a  familiar  example. 
It  is  an  oily  liquid,  composed  of  two  gases.     A  slight  eleva- 
tion of  temperature  will  cause  instant  decomposition,  even 
with  explosive  violence.     Generally  all    compounds    which 
contain  a  volatile  principle  are  easily  decomposed  by  a  high 
temperature.    Hence  caloric  sometimes  favors  chemical  action 
by  destroying  cohesion,  while  at  others  it  prevents  it,  and 
favors  decomposition  by  promoting  elasticity. 

2.  There  are  some  gases,  however,  which  readily  combine 
at  a  high  temperature,  as  in  the  case  of  gaseous   explosive 
mixtures.     Oxygen   and  hydrogen  gases  require  the  heat  of 
flame  to  effect  their  union.     The  caloric,  in  such  cases,  ac- 
cording to  Berthollet,  expands  the  gases  in  immediate  con- 
tact with  the  flame,  which  acts  as  a  violent  condensing  force 
to  contiguous  portions,  and  brings  them  within  the  sphere  of 
each  other's  attraction.     The  same  explanation  is  applied  to 
the  combination  of  gases  effected  by  passing  electric  shocks 
through  them. 

III.  Quantity  of  Matter.     Oxygen  combines  with  lead  in 

10 


110  Operation  of  Chemical  Affinity. 

three  proportions,  forming  three  distinct  compounds.  The 
peroxide,  or  that  which  has  the  greatest  quantity  of  oxygen, 
is  easily  decomposed  by  heat;  the  second  compound,  in 
which  there  is  less  oxygen,  requires  a  higher  temperature  to 
effect  decomposition ;  and  the  third,  which  has  the  least  oxy- 
gen, will  sustain  the  heat  of  our  furnaces  without  yielding  up 
its  oxygen.  Hence,  generally,  when  one  substance  combines 
with  another  in  several  proportions,  the  affinity  is  stronger  in 
the  case  of  the  less  than  of  the  greater  portions* 

On  this  principle,  also,  when  a  salt  is  dissolved  in  water, 
the  first  portions  are  dissolved  more  rapidly  than  the  last,  and 
the  force  of  affinity  diminishes  up  to  the  point  of  saturation, 
when  it  is  overcome  by  the  cohesion  of  the  solid. 

This  principle  led  Berthollet  to  account  for  all  chemical 
changes  without  the  aid  of  affinity,  the  existence  of  which  lie 
was  disposed  to  deny ;  but  M.  Dulong  has  found  that  the 
principle  of  Berthollet  is  not  in  accordance  with  the  results 
of  experiment. 

IV.  Gravity.    The  influence  of  gravity  on  chemical  action 
is  seen  when  substances  of  different  specific  gravities  com- 
bine;   as,  when  two   liquids  are   put   together,  the  heavier 
liquid  will  sink  to  the  bottom ;  or,  when  salt  is  dissolved  in 
water,  the  salt  will  remain   at  the  bottom,  and  prevent  the 
particles  of  water  from  coming    into  contact  with  those  of 
the  salt. 

V.  Imponderable  Agents.     The  influence  of  caloric  over 
chemical  phenomena  has  already  been  alluded  to.     It  favors 
chemical  action  in  the  case  of  solids,  by  destroying  cohesion, 
and  opposes  chemical  action  in  the  case  of  gases,  by  increas- 
ing their  elasticity.     The  influence  of  light  has  already  been 
noticed.     Common  electricity  is  often  employed  for  the  com- 
bination of  gases,  and  galvanism  for  decompositions ;   but  the 
same  effects  may  be  produced  by  either. 

*  In  consequence  of  the  influence  of  quantity  of  matter  over  chem- 
ical changes,  the  chemist  generally  employs  more  of  one  substance 
than  is  necessary  to  effect  the  decomposition  of  another. 


Measure  and  Effects  of  Chemical  Affinity.         Ill 

Measure  of  Affinity. 

Since  some  substances  have  a  stronger  affinity  than  others, 
attempts  have  been  made  to  measure  its  different  degrees  of 
force.  It  was  once  supposed  that  its  relative  strength  could 
be  ascertained  by  the  order  of  decomposition,  as  may  be  ex- 
plained from  the  following  table:  — 

Sulphuric  J3cid. 

Baryta,  Lime, 

Strontia,  Ammonia, 

Potassa,  Magnesia. 

Soda, 

If  to  the  sulphuric  acid,  united  with  the  magnesia,  forming 
the  sulphate  of  magnesia,  ammonia  be  added,  the  acid  will 
leave  the  magnesia,  and  elect  the  ammonia,  forming  the  sul- 
phate of  ammonia.  If  to  this,  lime  be  added,  the  acid  will 
desert  the  ammonia,  and  unite  with  the  lime ;  this  again  will 
be  decomposed  by  the  soda,  and  so  on  to  baryta.  Hence 
sulphuric  acid  has  the  strongest  affinity  for  the  baryta,  and 
the  force  is  in  the  order  in  which  the  several  substances  are 
arranged. 

/ '  //».  This  order  may  be  shown  experimentally  thus :  To  a  filtered  solu- 
tion of  nitrate  of  silver  add  metallic  mercury  ;  the  silver  will  be  precip- 
itated, and  the  nitric  acid  will  combine  with  mercury,  forming  the  nitrate 
of  mercury.  Immerse  in  this  a  piece  of  clean  sheet  lead;  the  mercury 
will  now  be  precipitated,  and  the  lead  will  remain  in  solution. 

Suspend  in  this  a  strip  of  clean  copper;  the  lead  will  be  thrown  down, 
and  the  nitrate  of  copper  will  remain  in  s'olution. 

In  this  place  a  sheet  of  bright  iron,  and  in  a  short  time  the  iron  will 
displace  the  copper,  forming  a  solution  of  nitrate  of  iron. 

To  this  present  a  piece  of  zinc ;  the  iron  will  be  separated,  and  the 
zinc  will  combine  with  the  acid. 

Add  liquid  ammonia  ;  the  zinc  will  be  separated,  and  nitrate  of  ammo- 
nia remain  in  solution. 

To  this  pour  lime  water;  the  ammonia  will  be  liberated  in  the  form 
of  a  j^as.  and  nitrate  of  lime  remain  in  solution. 

Add  to  this  oxalic  acid,  and  the  oxalate  of  lime  will  be  thrown  down, 
while  a  mixture  of  water  and  nitric  acid  remains. 

Hence  the  practical  chemist,  when  he  wishes  to  decom- 
pose any  compound,  is  enabled  to  decide  upon  the  substance 
which  will  produce  that  effect. 

But  the  circumstances  which  modify  the  action  of  chemical 
affinity  are  so  numerous,  that  the  order  of  decomposition  is 
not,  in  every  case,  the  measure  of  affinity.  To  determine  the 


112  Effects  of  Chemical  Affinity. 

relative  force  of  affinity  in  doubtful  cases,  observe  the  ten- 
dency of  several  substances  to  unite  with  the  same,  under 
the  same  circumstances  ;  and  then  notice  the  apparent  facility 
of  decomposition,  when  these  compounds  are  exposed  to  the 
same  decomposing  agent. 

/ 
Effects  of  Affinity. 

The  changes  which  accompany  the  action  of  affinity  are 
changes  of  chemical  properties  —  of  color,  form,  temperature, 
and  specific  gravity. 

I.  Change  of  Chemical  Properties.     It  is  one  of  the  most 
remarkable  facts  in  chemistry,  that,  when  two  bodies  combine 
chemically,  the  compound  is  generally  possessed  of  properties 
entirely  different  from  those  of  the  components. 

Ezp.  1.  Pour  sulphuric  acid  upon  magnesia,  and  the  compound  will 
be  Epsom  salts,  entirely  unlike  either. 

Exp.  2.  Burn  oxygen  and  hydrogen  gases,  and  water  will  be 
formed,  which  is  wholly  different  from  either  of  its  constituents. 

There  are  some  cases  in  which  affinity  produces  com- 
pounds without  much  change  of  properties,  as  in  the  case 
of  solution ;  but  the  force  of  affinity  in  such  cases  is  very 
feeble. 

Exp.   Salt  dissolved  in  water,  and  camphor  in  alcohol,  are  instances. 

II.  Change  of  color  is  often  the  effect  of  affinity. 

Exp.  1.  To  the  chloride  of  calcium  add  nitrate  of  silver,  both  in 
solution  ;  a  white  precipitate  will  be  formed,  which  is  the  chloride  of 
silver.  (See  page  69.) 

Exp.  2.  To  a  solution  of  nitrate  of  lead  add  a  few  drops  of  hydriodic 
acid,  and  a  beautiful  yellow  pigment  will  be  formed. 

Exp.  3.  Into  an  infusion  of  purple  cabbage  pour  a  few  drops  of  any 
alkali,  and  the  color  will  become  green  ;  add  an  acid  jrnis-i.-illy,  drop 
by  drop,*  and  the  purple  color  will  be  restored;  add  a  few  drops  more 

*  For  this  and  sim-  Fig.  53. 

ilar  purposes, the  drop- 
ping tube  a  (Fig.  53) 
may  be  used,  ft  is  a 
glass  tube,  with  a  bulb, 
as  «,  with  a  small  ap- 
erture at  the  smaller 
end,  through  which  any  liquid  may  be  drawn  up  into  the  bulb  by  pla- 
cing the  mouth  upon  the  larger  end.  Having  partially  filled  the  bulb, 
Elace  the  thumb  over  this  end,  and,  by  admitting  the  air  slowly,  the 
quid  will  drop  out  at  the  smaller  end. 


Effects  of  Chemical  Affinity. 


113 


Fi?.  54. 


of  acid,  and  it  will  become  red.  By  the  gradual  addition  of  the  alkali, 
the  effects  may  now  be  reversed. 

III.  Change   of  form   frequently    accompanies   chemical 
combination. 

E.rp.  1.  Take  oxygen  and  hydrogen  gases,  and  explode  them;  they 
will  form  a  liquid  —  water.  Hence  chemical  affinity  converts  gases  into 
liquids. 

I'.rp.  2.  If  the  two  gases, 
ammonia  and  the  hydrochlo- 
ric acid,  be  brought  together 
in  their  nascent  state,  i.  e., 
at  the  moment  of  their  for- 
mation, they  will  produce 
the  solid  hydrochlorate  of 
••'  ni'i'Miia.  Hence  chemical 
afrinity  converts  gases  into 
solids.  The  two  gases  may 
be  formed  by  putting  hy- 
drochlorate of  ammonia  and 

lime  in  one  retort,  (Fig.  54,)  and  liquid  hydrochloric  acid  in  the  other, 
and  applying  heat ;  as  the  gases  meet  in  the  glass  receiver  b,  they  will 
combine  and  form  a  white  solid. 

E.rji.  -T  Take  chloride  of  calcium  in  solution,  and  pour  in  sulphuric 
acid  ;  a  solid  precipitate  —  the  sulphate  of  lime  —  will  be  thrown  down 
Hence  affinity  converts  liquids  into  solids. 

Exp.  4.  Into  a  solution  of  pearlash  or  saleratus  pour  sulphuric 
acid,  and  a  portion  of  the  liquid  is  converted  into  the  form  of  a  gas, 
which  escapes  with  effervescence. 

l-lrjt.  Add  one  part  of  fuming  nitric  acid  to  two  of  alcohol ;  both  liquids 
will  be  converted  into  ammonia,  and  pass  off  in  gas.  Hence  affinity 
converts  liquids  into  gases.  ^ 

Eip.  5.  Mix  two  solids,  the  nitrate  of  ammonia  and  sulphate  of 
soda;  on  rubbing  them  in  a  mortar,  they  will  become  liquid.  Hence 
chemical  affinity  converts  solids  into  liquids. 

Erp.  6.  Explode  gunpowder;  it  will  be  wholly  converted  into  gas. 
Hence  chemical  affinity  converts  solids  into  gases. 

IV.  Change  of  Temperature.     The  heat  arising  from  the 
combustion  of  fuel,  is  owing  to  chemical  action. 

Exp.  Wet  a  piece  of  paper  with  spirits  of  turpentine  and  sulphuric 
acid,  and  then  throw  on  a  few  grains  of  chlorate  of  potassa;  the  paper 
will  instantly  be  in  flames. 

V.  Change  of  Specific  Gravity.     In  changes  of  gases  into 
liquids  or  solids,  or  of  the  latter  into  the  former,  there  is,  of 
course,  a  great  change  of  density.     But  where  there  is  no 
change  of  form,  there  is  usually  more  or  less  of  this  change. 

Exp.  Mix  100  measures  of  strong  sulphuric  acid  with  100  of  water, 
and  the  mixture  will  be  less  than  200  measures. 

10* 


114  Laws  of.  Chemical  Affinity. 


Laws  of  Chemical  Affinity. 

The  laws  which  regulate  the  action  of  affinity,  constitute 
the  most  important  part  of  the  whole  subject ;  for  they  are  the 
foundation  of  modern  chemistry.  As  they  are  expressed 
mathematically,  they  have  consequently  imparted  to  it  a  high 
degree  of  accuracy,  and  greatly  elevated  its  rank  as  a  science. 
Most  substances  have  been  found  to  combine  in  dt finite  f)ro- 
portions,  and  with  such  the  laws  of  affinity  are  chiefly  con- 
cerned ;  but  there  are  numerous  cases  of  apparently  indefinite 
proportions,  which  first  demand  a  separate  consideration. 

I.  Indefinite  Proportions.     Of  these  there  are  two  c: 

in  the  first  of  which,  any  quantity  of  one  substance  may  be 
combined  with  any  quantity  of  another.  Thus  a  drop  of 
alcohol  will  combine  with  a  quart  of  water,  or  a  drop  of  w.-itrr 
with  a  quart  of  alcohol. 

Exp.  Take  a  large  glass  vessel,  and  fill  it  nearly  full  of  water .  r.,]i.r 
it  purple  with  the  infusion  of  red  cabbage;  a  drop  of  sulphuric  :icid  will 
change  it  red,  or  a  drop  of  alkali  will  give  it  a  green  color,  which  shows 
that  both  the  acid  and  the  alkali  must  combine  with  the  whole  of  tin- 
water. 

In  the  second  case,  the  proportions  are  indefinite  within 
certain  limits.  Thus  with  2J  Ibs.  of  water,  a  pound  or  any 
less  quantity  of  common  salt  will  combine,  but  if  a  larger 
quantity  of  salt  be  employed,  all  the  excess  above  a  pound 
will  remain  undissolved.  The  limit  to  the  process  is  the 
point  o"t  saturation.  (See  page  108.) 

The  most  common  instances  of  indefinite  proportions  are 
solutions  where  the  proportions  are  indefinite  below  the  point 
of  saturation.  Instances  of  unlimited  indefinite  proportions 
are  less  numerous.  It  is  important  to  observe,  in  these  cases, 
that  the  force  of  affinity  is  usually  feeble,  and  the  change  of 
properties  slight.  Thus,  in  the  common  liquors,  the  properties 
of  the  alcohol  are  slightly  modified  by  its  combination  with 
water ;  and  in  solutions  there  is  also  little  change. 

II.  Definite  Proportions  by  Weight.    In  the  most  numerous 
and   interesting   cases   of  chemical  combination,  a  certain 
portion  of  one  substance  unites   with  one,  two,  three,  or 


Laws  of  Chemical  Affinity.  115 

more  times  a  given  weight  of  another.  These  cases  are 
usually  characterized  by  a  greater  energy  of  combination, 
and  a  much  greater  change  of  properties  than  thos^e  which 
have  been  described.  The  great  law  of  definite  proportions 
by  weight  may  be  thus  stated  :  — 

1.  The  proportions  in  which  substances  combine  may  be 
ef  pressed  by  fixed  numbers,  or  by  the  multiples  of  these  num- 
bers. The  following  table  is  an  illustration  :  — 


Water                   is  compo 
Binoxide  of  Hydrogen 
Protoxide  of  Nitrogen 
Binoxide 
Hyp'initrous  acid 
Nitrous  acid 
Nitric  acid                     *' 

>sed  of  Hydrogen    1  part  - 
"     .        1    "     - 
Nitrogen  14    "     - 
"           14    "     - 
"          14    "     - 
"          14    "     - 
"          14    "    - 

-  Oxygen  8  parts. 
«     16    " 
"      8    " 
"     .6    " 
L        «    24    " 
"    32    " 
u        «     40    " 

A  comparison  of  all  the  cases  shows  that  hydrogen  enters 
into  combination  in  less  quantity  relatively  than  any  other 
substance.  It  is  therefore  taken  for  a  standard  of  comparison, 
and  in  the  above  table  appears  as  unity.  The  lowest  ratio 
in  which  oxygen  combines  with  other  substances  is  eight 
times  that  of  hydrogen.  The  lowest  combining  ratio  of  nitro- 
gen is  fourteen.  If  any  simple  substance  does  not  combine 
with  hydrogen,  its  lowest  combining  ratio  may  be  ascertained 
from  its  combination  with  any  otter  substance,  whose  ratio 
has  been  determined.  Thus  from  the  above  table  the  com- 
bining ratio  of  nitrogen  is  seen  in  its  compounds  with  oxy- 
gen, whose  ratio  was  ascertained  in  its  compounds  with 
hydrogen.  The  lowest  combining  ratio  is  also  called  an 
equivalent,  or  proportional.  (See  page  107.) 

Inspection  of  the  above  table  will  show,  that  while  eight  is 
the  lowest  combining  ratio  of  oxygen,  it  combines  also  in  the 
ratio  of  16,  24,  32,  and  40  parts;  that  is,  two,  three,  four, 
and  five  times  the  lowest  r.itio,  agreeable  to  the  above-men- 
tioned law. 

There  are  some  cases  in  which  substances  do  not  unite 
with  one  equivalent  of  one  to  one,  two,  or  more  equivalents 
of  another,  but  apparently  of  one  to  one  and  a  half.  Such 
an  irregularity  conforms  to  the  general  law,  on  the  supposi- 


116  Laws  of  Chemical  Affinity. 

tion  that  two  of  the  former  unite  with  three  of  the  latter.  In 
some  cases,  also,  two  equivalents  of  one  substance  unite  with 
five  of  another. 

The  law  of  definite  proportions  by  weight  may  be  thus 
illustrated  algebraically  :  —  If  x  and  y  be  the  equivalents  of 
any  two  substances,  their  compounds  must  be  z+y,  x-f-2y, 
x-|-3y,  x  +  4y,  etc. ;  sometimes  we  shall  have  2x  +  3y, 
and  rarely  2  x-|-5  y. 

It  is  evident  from  the  above  that  the  equivalent  of  any 
compound  is  the  sum  of  the  equivalents  of  its  constituents, 
each  being  multiplied  by  the  number  of  times  it  enters  into 
the  combination.  Thus,  in  the  above  table,  the  equivalent  of 
water  is  l+8zr9,  of  nitric  acid,  14-f-40=54,  etc. 

2.  The  second  law  of  definite  proportions  is  the  follow- 
ing:— 

Every  substance  has  its  constitution  invariable.  Thus 
nitric  acid  is  always  composed  of  one  equivalent  of  nitrogen 
and  five  of  oxygen.  No  other  substances,  and  no  other 
number  of  equivalents  of  these,  by  combination  can  form 
nitric  acid. 

The  same  is  true  of  every  substance  whose  elements  com- 
bine in  definite  proportions.  The  least  change  of  these  de- 
terminate quantities  will  either  form  an  entirely  different  sub- 
stance, or  a  portion  of  that  substance  which  is  'n  excess  will 
remain  uncombined ;  hence  whatever  be  the  circumstances 
under  which  chemical  substances  are  formed,  whether  formed 
ages  ago  by  the  hand  of  nature,  or  quite  recently  by  the 
agency  of  the  chemist,  their  composition  is  always  inva- 
riable. 

The  merit  of  establishing  this  law  is  due  to  Wenzel,  a 
Saxon  chemist,  who  published  his  views  in  1777.  But  Dr. 
Dalton,  an  eminent  English  chemist,  discovered  the  first  law, 
and  deduced  from  the  scattered  facts  a  theory  of  chemical 
union,  embracing  the  whole  science,  and  first  published  in 
1803.  Drs.  Wollaston,  Thompson,  and  other  chemists,  fol- 
lowed out  these  views.  But  to  no  one,  in  this  department',  is 
science  so  much  indebted  as  to  Berzelius. 


Laics  of  Chemical  Affinity.  117 

The  application  of  these  laws,  in  the  arts,  is  of  immense 
importance.  In  the  manufacture  of  compounds,  they  teach 
precisely  what  proportions  of  the  ingredients  should  be  used. 
If  these  are  expensive,  an  excess  of  one  would  be  a  seri- 
ous loss. 

III.  Definite  Proportions  by  Volume.  The  principal  law 
of  definite  proportions  by  volume  is  precisely  similar  to  that 
of  definite  proportions  by  weight,  the  parts  being  determined 
by  measure,  as  in  the  former  case  by  weight.  This  law  holds 
true  only  in  the  case  of  gases  and  vapors.  It  is  supposed 
that  substances  which  have  not  yet  been  made  to  assume 
the  form  of  a  gas  or  vapor,  would  conform  to  this  law,  if 
they  should  assume  such  form.  The  law  may  be  illustrated 
by  the  following  table :  — 

100  vols.  carbonic  acid  gas  combine  with  100  of  ammoniacal  gas. 
u  «  u  u  200  " 

"        fluoboric         "  "  100  " 

«  "  «  »  200  " 

But  there  are  two  laws  of  definite  proportions  by  volume, 
which  do  not  hold  true  to  the  same  extent  in  definite  propor- 
tions by  weight.  The  first  is,  that  a  simple  ratio  of  one  to 
two,  one  to  three,  &,c.,  exists  between  the  volumes  of  differ- 
ent constituents  in  the  same  compound.  This  may  be  seen 
in  the  above  table. 

The  second  law  is,  that,  in  combination,  gases  and  vapors 
are  condensed  by  a  portion,  which  is  in  a  simple  ratio  to  the 
volume  of  one  of  the  constituents. 

The  laws  of  definite  proportion  by  weight  and  by  volume 
are  not  inconsistent  with  each  other,  for  the  specific  gravity 
always  bears  such  a  relation  to  the  combining  ratio  by  volume 
as  to  establish  their  harmony.  Thus  hydrogen  and  oxygen 
combine  in  the  ratio  of  two  of  the  former  to  one  of  the  latter 
by  volume,  and  of  one  to  eight  by  weight.  But  as  oxygen  is 
sixteen  times  heavier  than  hydrogen,  one  volume  of  it  is  eight 
times  as  heavy  as  two  of  the  latter.  In  other  words,  the 
compound  ratio  of  the  specific  gravity  and  of  the  equiva- 
lents by  volume,  is  equal  to  the  ratio  of  the  equivalents  by 
weight. 


118  The  Atomic   Theory. 

Atomic  Theory. 

Existence  of  Atoms.  The  atomic  theory  supposes  matter 
to  be  composed  of  minute,  indivisible  atoms.  Hypotheti- 
cally,  matter  is  infinitely  divisible,  that  is,  to  Almighty  power; 
but  in  fact  it  is  not  infinitely  divided.  Sir  Isaac  Newton  re- 
garded it  as  probable,  "that  the  primitive  particles,  being 
solids,  are  incomparably  harder  than  any  porous  bodies  com- 
pounded of  them,  even  so  very  hard  as  never  to  wear,  or 
break  in  pieces;  no  ordinary  power  being  able  to  divide  what 
God  himself  made  one  in  the  first  creation." 

Theory  of  definite.  Proportions  by  Weight.  When  sub- 
stances combine  in  their  lowest  equivalents,  they  unite  atom 
to  atom,  (Fig.  55 ;)  Fig.  55. 

in  higher  proportions, 
one    atom    of  one   to 

two,   three,   or   more  

atoms    of  the   other. 

This  theory  exactly  accounts  for  the  facts  of  definite  propor- 
tions; for  if  in  one  compound  we  have  one  atom  of  A 
joined  to  one  of  B,  and  in  another  one  of  A  joined  to 
two  of  B,  through  the  whole  mass,  the  sum  total  of  B  in  the 
latter  case  will  be  exactly  twice  as  much  as  in  the  former 
case. 

Atomic  Weight.  If  in  a  compound  of  one  grain  of  hydro- 
gen with  eight  of  oxygen  there  be  an  equal  number  of  atoms 
of  each,  an  atom  of  the  latter  will  be  eight  times  as  heavy  as 
an  atom  of  the  former.  In  this  way  we  know  the  relative 
weights  of  the  atoms  of  all  substances,  whose  equivalents  are 
known.  As  the  numbers  are  the  same,  the  terms  are  often 
interchanged. 

The  absolute  weight  and  magnitude  of  atoms  cannot  be 
determined.  Dr.  Thompson  calculates  that  a  cubic  inch  of 
lead  contains  more  than  883,492,000,000  atoms. 

The  shape  of  atoms  is  matter  of  hypothesis.  They  are 
generally  supposed  to  be  spheroidal. 


Isomerism. —  Cause  of  Chemical  Affinity.  119 

Isomerism. 

It  was  formerly  supposed  that  when  two  elements  combine 
in  the  same  ratio,  they  must  always  give  rise  to  the  same 
compound ;  but  it  has  of  late  been  discovered  that  this  is  not 
always  the  case.  Thus  there  are  3  compounds  of  oxygen 
and  phosphorus,  whose  composition  is  identical,  each  being 
composed  of  31.4  parts  by  weight  of  phosphorus,  and  40 
parts  by  weight  of  oxygen ;  and  yet  these  substances  differ  in 
their  properties.  The  same  is  true  of  the  two  cyanic  acids. 
Berzelius  has  applied  to  such  compounds,  as  a  class,  the 
general  term  isomcric,  from  two  Greek  words,*  which  ex- 
presses an  equality  in  the  ingredients;  and  to  distinguish  the 
isomeric  bodies  from  each  other  the  terms  parai  and  mcta 
are  prefixed.  » 

To  reconcile  the  phenomena  of  isomerism  with  the  theories 
of  chemical  combination,  we  have  only  to  suppose  that  the 
same  elements  may  combine  in  different  ways,  so  as  to  give 
rise  to  compounds  essentially  distinct;  for  example,  we  may 
suppose  that  the  2  atoms  of  phosphorus  and  the  5  atoms  of 
oxygen,  which  form  3  isomeric  bodies,  may  be  grouped  dif- 
ferently; thus,  2  atoms  of  oxygen  may  first  unite  with  the 

2  of  phosphorus,   and  this  compound  unite  with  the  other 

3  atoms  of  oxygen,  or  4   of  oxygen    may  unite  with  1  of 
phosphorus,  and  1  of  oxygen  with  1  of  phosphorus  :  these  two 
compounds   may   then  combine,  and    form  a   different  sub- 
stance from  the  first,  although  both  contain  the  same  number 
of  atoms  of  each  element.     It  is  evident  that  these  groups 
may  be  varied  still  further;  hence  the  kind  of  substance  may 
depend  upon  the  order  in  which  the  atoms  are  united.     In  a 
few  cases,  the  equivalents  of  isomeric  bodies  differ :   defiant 
gas  and  etherine  are  an  example.     The  equivalent  of  olefiant 
gas  is  14.24,  and  that  of  etherine  28.48,  or  exactly  double. 

Cause  of  Chemical  Affinity. 

The  cause  of  affinity  is  probably  electricity.  In  those 
cases  where  the  electrical  state  of  substances  can  be  ascer- 
tained, they  are  always  found  to  be  oppositely  electrified, 

*  loos,  equal,  and  /te^oj,  part.  t  Ilc/yct,  near  to. 


120  Cause  of  Chemical  Affinity. 

when  combination  takes  place.  Voltaic  electricity  is  the 
most  powerful  decomposing  agent,  and  the  whole  phenomena 
of  electro-chemical  decomposition  seem  to  prove  the  identity 
of  affinity  and  electricity.  This  view  accords  best  with  the 
simplicity  every  where  observed  in  the  laws  of  nature.  By 
ascribing  the  phenomena  of  electricity,  galvanism,  mag- 
netism, and  chemical  affinity,  to  the  same  agent,  we  seem  to 
be  progressing  in  the  chain  of  causation  nearer  to  the  great 
and  ultimate  cause,  the  agency  of  God.  Some  suppose  that 
what  we  call  the  agents  and  laws  of  nature,  have  no  real 
existence  as  distinct  powers.  They  deny  the  agency  of 
second  causes,  and  ascribe  every  operation  of  nature  to  the 
immediate  power  of  God.  Others  suppose  that  there  are 
real  agents  or  causes  dependent  upon  God,  but  possessed  of 
power  in  themselves,  to  act  as  second  causes,  or  subordinate 
agents,  in  the  various  phenomena  of  matter.  Whichever 
view  we  take,  we  must,  in  the  end,  refer  the  ultimate  cause 
to  the  impulse  of  the  divine  will ;  although,  for  the  mere 
purposes  of  scientific  classification,  something,  perhaps,  is 
gained  by  the  introduction  of  second  causes. 


PART    III. 

PONDERABLE    BODIES 


Specific  Gravity  means  the  relative  weight  of  different 
substances,  compared  with  some  standard.  In  the  case  of 
solids  and  liquids,  the  weight  of  the  body  is  compared  with 
water  as  unity  ;  i.  e.,  if  a  given  quantity  of  water  by  measure 
be  weighed,*  and  that  weight  represented  by  1,  the  weight 
of  an  equal  quantity  by  measure  of  any  other  substance  is 
compared  with  it.  In  the  case  of  gases,  air  is  taken  for  the 
standard  of  comparison,  or  for  unity,  and  an  equal  quantity 
of  any  other  gas  is  weighed,  and  compared  with  it. 

There  are  several  methods  of  ascertaining  the  specific 
gravities  of  bodies. 

1.  One  of  the  best,  if  the  body  is  a  Fig.  56. 
solid,  is  to  weigh  it  in  the  air,  and  then 

in  water,  in  a  manner  represented  in 
Fig.  56.  If  the  body  weighs  100  grains 
in  the  air,  and  (50  grains  in  water,  then, 
to  ascertain  its  specific  gravity,  institute 
the  following  proportion:  As  100  —  60, 
or  49  :  100  :  :  1  ;  2.5;  hence  the  sp.  gr. 
of  the  body  is  2.5,  or  two  and  a  half 
times  as  heavy  as  water.  If  the  solid  is 
lighter  than  water,  suspend  to  it  a  body 
heavier  than  water,  whose  specific  gravity 
is  known,  and  then  weigh  it  as  in  the  first  instance. 

2.  To  ascertain  the  specific  gravity  of  liquids,  the  Areom- 
eter  is    a   convenient   instrument.      It  consists   of  a  tube, 


A  cubic  foot  of  distilled  water  weighs  62.5  Ibs. 
11 


122  Nomenclature. 

a,  (Fig.  57,)  graduated  with  numbers,  upon  the  end     Fig-  57. 

of  which  are  two  balls,  the  lower  filled  with  mer-          U 

cury.     If  the  instrument  sink  in  distilled  water  to 

1,  it  will   sink  below  that  mark  in  liquids  which 

are  lighter  than  water,  and  will    remain  above  it 

.n  those  which  are  heavier.     The  specific  gravity 

of  each  liquid  is  thus  ascertained  by  the  numbers    I     v  ' 

on  the  scale. 

The  specific  gravity  of  liquids  is  also  ascertained    5(H||jjl|IJi|§^ 
by  the  use  of  a  small  bottle  containing  just  1000 
grains  of  water;  by  filling  it  with  any  other  liquid,  its  weight 
will  express  directly  its  specific  gravity. 

3.  The  specific  gravity  of  gases  is  more  difficult  :  a  given 
portion  of  air  is  carefully  weighed  in  a  thin  glass  flask ;  the 
air  is  then  exhausted,  and  the  flask  weighed ;  the  difference 
gives  the  weight  of  the  air ;  this  is  taken  for  unity,  and  the 
weight  of  an  equal  quantity  of  any  other  gas  is  compared 
with  it;  thus,  100  cubic  inches  of  dry  air,  at  60°  F.  and 
30  in.  barometer,  weigh  31.0117  grains;  100  cubic  inches  of 
oxygen  weigh  34.109  grains.  Now,  to  ascertain  the  sp.  gr. 
of  oxygen,  institute  the  following  proportion  :  — 

As  31.0117  :  34.109  :  :  1,  the  sp.  gr.  of  air,  to  1.10:J.",, 
the  sp.  gr.  of  oxygen.  The  sp.  gr.  of  any  other  gas  may  be 
found  in  the  same  way. 

Nomenclature. 

The  study  of  particular  substances  has  been  greatly  facili- 
tated by  the  introduction  of  the  nomenclature.  By  the  use  of 
systematic  names,  expressive  of  the  constitution  of  substances, 
the  recollection  of  the  name  will  call  to  mind  the  constitu- 
tion ;  while,  on  the  other  hand,  if  there  be  any  difficulty  in 
remembering  names,  the  constitution  will  at  once  show  what 
the  name  must  be.  Hence,  although  compounds  are  very 
numerous,  the  student  can  have  no  difficulty  in  remembering 
their  names  and  constitution,  for  the  one  necessarily  suggests 
the  other. 

The  present  nomenclature  was  introduced  in  1787  by  the 
French  chemists.  It  resulted  from  the  labors  of  Lavoisier, 
Berthollet,  Guyton-Morveau,  and  Fourcroy.  Since  that  time, 
it  has  undergone  but  a  few  slight  changes.  The  former  no- 


Nomenclature. 


123 


menclature,  if  such  the  entire  want  of  system  could  be 
called,  was  barbarous  in  the  extreme ;  fanciful  names  were 
introduced,  and  often  many  such  were  attached  to  the  same 
substance. 

I. Simple  Substances.  The  names  of  such  elementary  sub- 
stances as  had  long  been  known,  remain  unaltered,  as  of 
gold,  iron,  etc.  Those  which  have  been  discovered  within 
the  period  of  modern  chemistry,  have  received  names  ex- 
pressive of  some  obvious  property;  thus  the  name  oxygen 
signifies  a  generator  of  acids ;  iodine,  violet-colored,  from 
the  beautiful  color  of  its  vapor ;  chlorine,  green,  from  the 
color  of  the  gas.  The  following  are  the  names  of  the  simple 
substances,  with  their  symbols  annexed  :  — 


Oxygen, O. 

Chlorine, Cl. 

Iodine, I. 

Bromine, Br. 

Fluorine, F. 

Hydrogen, H. 

Nitrogen, N. 

Carbon, ". C. 

Sulphur, 8. 

Phosphorus, P. 

Boron, B. 

Silicon, Si. 

Selenium, Se. 

Potassium,  (Kalium,) K. 

Sodium,  (Natrium  ) Na. 

Lithium, L. 

Barium, Ba. 

Strontium, Sr. 

Calcium, Ca. 

Magnesium, Mg. 

Aluminium, Al. 

Glucinum, .' G. 

Yttrium, Y. 

Thorium, Th. 

Zirconium, Zr. 

Manganese, Mn. 

Iron,  (Ferrum,) Fe. 

Zinc,.  ..Zn. 


Cadmium, Cd. 

Tin,  (Stannum,) Sn. 

Cobalt,   Co. 

Nickel,    „ Ni. 

Arsenic, As. 

Chromium, Cr. 

Vanadium, V. 

Molybdenum, Mo. 

Tungsten,  (Wolfram,) W. 

Columbium,  (Tantalum,) Ta. 

Antimony  y  (Stibium,) Sb. 

Uranium, U. 

Cerium, Ce. 

Bismuth, Bi. 

Titanium, v  .Ti. 

Tellurium, Te. 

Copper,'(Cuprum.) Cu. 

Lead,  (Plumbum,) Pb. 

Mercury,  (Hydrargyrum,) . . :  .Hg. 

Silver,  (Argentum,) Ag. 

Gold,  (Aurum,) Au. 

Platinum, PL 

Palladium, Pd. 

Rhodium, R. 

Osmium, Os. 

Iridium, Ir. 

Latanium La 


Q.Acid  Compounds.  The  names  of  acid  compounds  have  a 
peculiar  construction.  All  the  acids  formed  by  combination 
of  oxygen  with  other  substances,  including  a  great  majority 
of  the  whole  number,  take  the  name  of  the  other  substance, 
(which  is  called  the  base,)  changing  its  termination.  If  there 


124  Nomenclature. 

be  two  oxygen  acids  formed  with  the  same  substance,  the 
stronger,  which  contains  more  oxygen,  takes  the  termination 
ic,  and  the  weaker,  ous.  In  the  case  of  more  numerous 
acid  compounds,  the  prefix  hypo  signifies  inferiority,  as  in 
the  following  of  oxygen  with  sulphur,  beginning  with  the 
stronger,  and  proceeding  to  the  weaker : — 

Sulphuric  acid,  Sulphurous  acid, 

Hyposulphuric  acid,  Hyposulphurous  acid. 

Sometimes  the  prefix  per  is  used  to  indicate  an  additional, 
but  indefinite  quantity  of  oxygen.  Thus  pirchluric  acid 
contains  more  oxygen  than  chloric  acid. 

Acids  which  do  not  contain  oxygen  receive  names  which 
>are  compounded  of  the  names  of  their  constituents,  the  first 
enunciated  terminating  in  o,  and  the  last  in  ic ;  as,  chloro- 
carbonic  acid.  Often  the  first  is  shortened  ;  as,  fluo-boric,  in- 
stead of  fluro-boric  :  this  is  the  case  with  the  hydrogen  acids ; 
as,  hydrochloric  acid,  hydrosulphuric  acid. 
3.  Primary  Compounds  which  are  not  Acids.  In  such  com- 
pounds, the  names  are  composed  of  the  names  of  their  con- 
stituents. In  the  compounds  of  oxygen,  chlorine,  iodine, 
bromine,  and  fluorine,  with  other  substances,  they  are  first 
enunciated,  and  receive  the  termination  ide ;  as,  oxide  of  iron, 
chloride  of  iron,  iodide  of  mercury,  bromide  of  carbon, 
fluoride  of  zinc.  In  their  compounds  with  each  other,  the 
order  of  enunciation  is  not  essential,  although  it  is  com- 
monly that  in  which  they  are  above  mentioned;  thus  we 
may  say,  chloride  of  bromine,  or  bromide  of  chlorine;  but  the 
former  is  more  common. 

Compounds  of  the  other  non-metallic  substances  with  each 
other  and  with  the  metals,  receive  names  of  similar  construc- 
tion, except  that  the  termination  urct  takes  the  place  of  idc ; 
as,  carburet  of  iron,  bicarburet  of  hydrogen,  sulphuret  of 
arsenic. 

In  many  cases,  one  substance  unites  with  another  in 
several  proportions,  and  the  compounds  are  designated  by 
numeral  prefixes — proto  the  first,  bi  (formerly  dcuto  was  used) 
the  second,  fpr  the  third,  ouadro  the  fourth,  etc.,  and  per  the 


Nomenclature.  125 

highest  degree,  but  indefinite ;  scsqui  signifies  one  and  a  half. 
If,  however,  the  last  enunciated  substance,  or  base,  be  in  two 
or  more  proportions,  the  dividing  prefixes  di,  triy  etc.,  are 
used;  subsequi  indicates  one  and  a  half  of  the  base. 

The  following  table  exhibits  all  the  cases  of  the  use  of 
numeral  prefixes : 

Triphosphuret  of  copper  =1  equiv.  phosphorus  and  3  equiv.  copper. 


of  copper  =•  1      "      oxygen         and  2 


copper. 

Subses.juiphospliuret  of  copper     =1      "      phosphorus  and  1  £  copper. 

Protoxide  of  copper                         =1      "      oxygen        .and  1  copper. 

Sexjuinxide  of  manganese            =  ^4    "      oxygen         and  1  '     manganese. 

Binoxide  of  manganese                 =2     "      oxygen         and  1  manganese. 

Trriodide  of  nitrogen                      =3     ««      iodine           and  1  nitro»en. 

Quad rochloride  of  nitrogen            =4     "      chlorine       and  1  "      nitrogen. 
Peroxide  of  iron  =  iron  oxidated  in  the  highest  degree. 

Many  metals,  whose  names  terminate  in  urn,  merely  change 
ium  or  um  into  a  to  indicate  the  state  of  protoxide.  Thus 
potassa  —  protoxide  of  potassium,  lithia  —  protoxide  of  lithi- 
um, etc.  The  protoxide  of  calcium  has  long  been  known  by 
the  name  of  lime. 

Alloys,  or  compounds  of  metals  with  each  other,  not  being 
yet  reduced  to  the  laws  of  definite  proportions,  have  no  sys- 
tematic names. 

Some  primary  compounds,  whose  combinations  are  analo- 
gous to  those  of  simple  substances,  receive  simple  names, 
which  in  composition  receive  the  termination  uret,  and  follow 
the  rules  above  given.  These  are  ammonia  and  cyanogen. 
Another  primary  compound,  water,  forms  compounds  which 
are  called  hydrates  ;  as,  hydrate  of  lime. 
4.  Secondary  Compounds,  or  Salts.  These  are  formed  by  the 
combination  of  acids  with  other  primary  compounds,  which 
are  called,  in  reference  to  them,  bases.  The  name  of  a  salt 
is  composed  of  the  names  of  the  acid  and  base.  If  the  name 
of  the  acid  have  a  termination  ic,  it  is  changed  into  ate ;  ous 
is  changed  into  ite.  Numeral  prefixes  are  used  according 
to  the  rules  which  have  been  given,  as  in  the  following  ex- 
amples :  — 

Dinitrate  of  the  protoxide  of  lead  =r  1   cq.  nitric  acid  and  2  eq.  protoxide  of  lead. 
Protonitrate  of  mercury  =  1    "  «  and  1  "         "    of  mercury. 

Sesqui-ulphate  of  potassa  =  1£  "  sulphuric  acid  &  1  "    potassa. 

Bisulphateof  peroxide  of  mercury  =  2    "  "  and  1  «'    perox.  of  mercury. 

Tersulphate  of  alumina  =3  "          and  1  "    alumina. 

11* 


1*26  Notation. 

As  the  acids  never  unite  with  the  metals  directly,  but  gen- 
erally with  their  oxides,  and  sometimes  other  compounds,  in 
the  case  o/  the  oxides,  the  name  is  abbreviated:  thus,  by 
protonitrate  of  mercury  is  always  understood  protonitrate  of 
the  protoxide  of  mercury.  Also,  the  prefix  proto  is  often 
understood,  and  we  say,  nitrate  of  mercury. 

There  are  many  secondary  compounds,  little  known,  how- 
ever, except  to  the  chemist,  called  sulphur  salts,  and  haloid 
salts,  whose  nomenclature  follows  the  rules  of  primary  com- 
pounds which  are  not  acid. 

Notation. 

Notwithstanding  the  great  advantages  of  the  chemical  no- 
menclature, a  much  greater  help  is  given  to  the  student  in 
the  notation.  By  this,  as  in  algebra,  long  and  intricate  pro- 
cesses are  exhibited  to  the  eye  at  a  glance,  and  the  relations 
of  the  constituents  in  complicated  compounds  easily  compre- 
hended. Each  element  is  represented  by  a  symbol  consisting 
of  its  initial,  or,  in  the  case  of  two  or  more  which  have  the 
same  initial,  of  the  initial  and  one  of  the  following  letters, 
as  on  page  123,  where  the  symbols  of  all  the  elementary 
substances  are  given.  In  the  case  of  potassium,  sodium, 
tin,  iron,  and  several  others,  the  symbols  are  derived  from 
the  Latin  names. 

The  symbols  of  compounds  are  composed  of  the  symbols 
of  their  constituents,  algebraically  connected;  as,  Fe-|-Cl, 
chloride  of  iron.  In  primary  compounds,  the  sign  -(-  is  often 
omitted.  Coefficients  are  used  to  show  the  number  of  equiv- 
alents; as,  N-|-4C1,  quadrochloride  of  nitrogen ;  or,  if  several 
symbols  are  written  together  without  the  sign  -)-,  an  index  is 
substituted  for  the  coefficient,  because  the  coefficient  multi- 
plies all  which  come  between  it  and  the  next  sign.  Thus 
the  symbol  of  the  substance  last  mentioned  may  be  written 
NCI4. 

Cyanogen,  ammonia,  and  water,  although  compounds,  have 
simple  symbols,  like  the  elements ;  thus  we  have  Cy,  Am,  and 
Aq,  (Aqua,)  instead  of  NC',  H3N,  and  HO. 


Notation,  127 

The  symbols  of  oxygen  and  sulphur  are  abbreviated.  The 
symbols  for  the  compounds  of  oxygen  are  written  thus : — 
N  for  N  +  5O,  N  for  N  +  4O,  N  for  N.+  3O,  etc.,  each  dot 
indicating  an  equivalent  of  oxygen.  A  comma  is  used  in  the 
same  manner  for  the  compounds  of  sulphur ;  thus,  P  for  PS. 
In  place  of  the  coefficient  2,  a  dash  is  often  drawn  through  or 
beneath  the  symbol.  This  is  very  convenient  in  the  case  of 
half  equivalents ;  as,  Mn,  signifying  2Mn  -|-  3O,  that  is,  Mn-f- 
1JO,  sesquioxide  of  manganese.  In  compounds  of  compli- 
cated constitution,  it  is  often  necessary  to  multiply  several 
terms  by  one  number,  or  to  connect  them  as  a  whole  to 
another  term.  This  is  done,  as  in  algebra,  by  the  use  of 

vincula  or  parentheses ;  thus  (K-(-2S)-{- Aq,  shows  that  Aq 
is  combined  with  K-)-2S,  as  with  one  substance;  but  if  the 
parentheses  were  omitted,  thus,  K -|- 2S -j- Aq,  the  symbol 
would  indicate  a  combination  of  three  distinct  substances, 
each  one  with  the  other.  Also  in  2(K+2S),  the  first  coeffi- 
cient belongs  to  what  is  within  the  parentheses  as  to  one 
substance. 

If  the  student  will,  for  practice,  explain  the  constitution  and 
give  the  names  of  the  compounds  in  the  annexed  table,  he  will 
become  familiar  with  the  rules  of  nomenclature  and  notation. 

The  following  table  contains  the  names,  equivalents,  and 
symbols  of  the  thirteen  non-metallic  elements,  and  the  sym- 
bols of  their  compounds  with  each  other,  in  the  order  in 
which  they  are  described  in  this  work :  — 

Oxygen,  equiv.  8 ;  symbol,  O. 

Chlorine,      «     35.42    «      Cl,  Cl  +  O,  C1  +  4O,  C1  +  5O,  Cl  -|-7O. 

Iodine,         "  126.3      "       I,  I  +  5O,  I  -f  7O,  3d  -f  I. 

Bromine,      "    78         "      Br,  Br  -f-  5O  or  BrO5. 

Fluorine,      "     18.68    "      F. 

Hydrogen  «  1  «  J  H,  H  +  O  or  H,  H  +  2O  or  H,  H-f  Cl, 
Hydrogen,  $  H  + 1,  H  +  Br,  H  +  F  or  HF. 

Nitrogen,     «     14.15    ««    $  *>  NO  or  N,  NO*  or  N,  NO3  or  N,  NO< 
^  or  N,  NO5  or  N,  NCI4,  NF,  NHS. 


128  Chemical  Substances.  —  Oxygen. 

c,  c,  c,  c  +  ci,c«ci5,  c*ci,  cci3, 

r»rK™          -    fi  10  C1i  CH2,  C«HS,  C<H«,  C«H3,  C«H5,  C10H* 

Carbon,  equ.v.6.12,  sym.        li§  j,c     £        c'  3^  c  C1 


,  HCyS«,  CyS«,  H*CyS«. 
Sulphur,      "16.1      M     *S,  S0«,  SO',  SO*,  S0>,  S'Cl,  SCI,  HS, 
(  HS»,  CS*. 


Phosphorus  "    15  7      «     J  P'  pl°'  p3°'  P'03'  pSO5>  pSCI3»  PSC15»  P1» 
™'  '  {  P8!3,  PBr,  P*Br»,  H3PS. 

Boron,         "    10.9      "        B,  B-f-  3O,  B-f-3Cl,  B-f  3F. 

r  Se,  Se-f-O  or  Se,  Se-f  2O  or  Se,  Se4-3O 
Selenium,  "     39.6      " 

Cor  Se. 

Silicon,       »    22.5      «        Si,  Si-j-O,  SiCl,  SiBr,  SiS,  SiF. 


CHAPTER    I. 

CHEMICAL    SUBSTANCES. 

+ 

These  substances  will  be  arranged  in  three  classes  :  1st, 
non-metallic  elements,  and  their  primary  compounds,  with 
each  other  ;  2d,  metals,  with  their  primary  compounds  ;  and 
3d,  secondary  compounds,  or  salts. 

Class  I.  Non-metallic  Elements  and  their  Primary  Com- 
pounds with  each  other. 

SECT.  1.     OXYGEN. 


Symb.O. 

History.  Oxygen  was  discovered  by  Dr.  Priestley,  of  Eng- 
land, August,  1774,  by  exposing  the  red  oxide  of  mercury  to 
the  solar  focus.  It  was  also  discovered  by  Scheele,  a  Swe- 
dish chemist,  in  1795,  and  the  same  year  by  Lavoisier,  of  Paris, 
neither  being  acquainted  with  the  discovery  by  the  others. 
The  honor  of  the  discovery,  as  is  usual  in  such  cases,  is  as- 
cribed to  Priestley,  who  called  it  dephlogisticatcd  air;  S»heele 
gave  it  the  name  of  empyreal  air  ;  Condorcet,  vital  air  ;  and 
Lavoisier,  oxygen.  This  latter  name  was  suggested  from  the 
belief  that  it  was  the  only  acidifying  principle  in  nature.  It 


Pneumatic  Cistern.  129 

is  derived  from  two  Greek  words,*  signifying  a  generator  of 
acids.  It  has  since  been  found,  however,  that,  although 
present  in  most  acids,  it  is  not  the  only  substance  capable 
of  forming  acid  compounds.  But,  as  a  great  majority  of  acids 
are  oxygen  acids,  the  name  is  not  inappropriate. 

Natural  History.  Oxygen  is  the  most  abundant  substance 
known.  It  forms  £  of  the  atmosphere,  f  part  of  water.  By 
far  the  greater  part  of  the  solid  crust  of  the  earth  is  composed 
of  oxydized  substances,  and  it  will  not  be  far  from  the  truth, 
if  we  estimate  oxygen  to  constitute  f  of  all  the  matter  with 
which  we  are  acquainted.f 

Processes.  Oxygen  can  easily  be  obtained  from  the  oxides 
of  metals,  and  from  some  of  the  salts.  The  oxides  of  man- 
ganese and  of  lead,  and  the  chlorate  of  potassa,  are  most 
commonly  used.  The  separation  is  effected  by  exposing 
these  substances  to  a  red  heat,  in  an  iron  retort,  connected 
by  a  pipe  with  the  pneumatic  cistern. 

For  the  collection  of  gases  which  are  not  absorbed  by 
water,  the 

Pneumatic  Cistern  is  Fig.  55. 

generally  employed.  It 
consists  of  an  oblong 
box,  C,  (Fig.  58,)  made 
water-tight ;  b  b,  two 
shelves  to  support  re- 
ceivers, as  r ;  ID,  a  well 
filled  with  water,  across 
which  a  board  is  placed, 
also  to  support  receiv- 
ers, with  small  holes  to 
let  the  gas  through  as  it 
comes  from  the  retort,  which  is  placed  over  the  side  of  the 
box.  The  shelves  b  b  may  be  made  for  gasometers,  or  gas- 
holders ;  and  in  that  case  they  are  boxes  open  at  the  bottom 
of  the  cistern,  with  stop-cocks  passing  through  one  corner  in 
the  top  of  each.  These  are  made  air-tight  by  a  lining  of 
sheet  lead.  When  they  are  filled  with  water,  the  gas  is  in- 
troduced, by  means  of  a  lead  pipe,  through  an  aperture  in  the 

*  *  O^v$  and  yirwitn. 

t  If  we  suppose  the  sun  and  planets,  with  the  stellary  systems,  to  be 
composed  of  matter  similar  to  our  earth,  the  quantity  of  oxygen  which 
actually  exists  must  be  immeasurably  great. 


130  Oxygen. 

side  of  each,  near  the  bottom;  as  it  rises  up,  it  displaces  the 
water;  /  is  a  lamp-stand  and  retort,*  as  it  is  connected  with 
the  cistern. t 

Theory.  To  understand  the  theory  of  the  process  by  man- 
ganese, it  is  necessary  to  notice  the  composition  of  its  three 
oxides. 

Manganese.  Oxygen. 

Protoxide,         27.7  or  I  equiv.  -f-    8  or  1     equiv.  =  35.7 
Sesquioxide,     27.7        "  -f-12orli       «      =39.7 

Peroxide,          27.7        "  -j-  1(i  or  2         "      =  43.7 

The  oxygen  may  be  separated  from  the  binoxide  in  two 
ways :  — 

1.  By  simply  exposing  it  to  a  red  heat.     In  this  case,  the 
binoxide  parts  with  £  equiv.  of  oxygen,  and  is  converted  into 
sesquioxide.     1  oz.  of'manganese  will  yield  128  cubic  inches 
of  oxygen. 

2.  By  putting  it,  in  fine  powder,  into  a  glass  flask,  with  an 
equal  weight  of  concentrated  sulphuric  acid,  and  heating  the 
mixture  by  a  spirit  lamp,  the  manganese  parts  with  one  equiv. 
of  oxygen,  and  the  sulprmte  of  the  protoxide  of  manganese 
remains.     About  twice  the  quantity  of  gas  is  obtained  by 
this  process,  1  oz.  yielding  256  cubic  inches  of  gas.     But  the 
former  method  is  most  convenient  in  practice. 

For  these  processes,  the  manganese  should  be  previously 
ascertained  to  be  free  from  carbonate  of  lime,  which  yields 
carbonic  acid  gas  on  being  heated. \  Oxygen  obtained  in 
this  way  is  not  quite  pure,  but  is  sufficiently  good  for  all  pur- 
poses of  experiment. 

The  gas  obtained  from  chlorate  of  potassa  is  much  purer, 
but  more  expensive. 

It  may  be  easily  obtained  by  subjecting  the  salt  to  a  dull 
red  heat  in  a  green  or  white  glass  flask,  made  without  lead, 

*  Jletorts  are  either  plain,  as  in  Fig.  Fig.  59. 

58,  or  tubulated,  as  Fig.  59.  A  Florence 
flask  will  answer  a  good  purpose,  if  a  lead 
tube  is  fitted  to  it.  See  Fig.  60. 

t  The  cistern  may  be  made  of  wood,    / 
or,  what  is  better,  of  copper,  of  any  con-  /     - 
venient  dimensions.     One  five  feet  long,  \ 
twenty  inches  wide,  and  twenty  inches 
in  height,  is  sufficiently  large  for  com- 
mon purposes. 

$  It  may  be  freed  from  carbonate  of  lime  by  washing  it  in  dilute 
hydrochloric  acid. 


Physical  and  Chemical  Properties. 


131 


or  in  an  iron  retort.*     It  first  becomes  liquid,  and  is  then 
resolved  into  oxygen  and  chloride  of  potassium. 

Theory.  The  chlorate  of  potassa  is  composed  of  chloric  acid  and 
potassa,  and  the  theory  of  the  process  may  be  thus  explained  :  KO  -|- 
CLO3  are  resolved  into  K-f-CL,  which  remains  in  the  flask,  and  0 
equiv.  of  oxygen,  which  are  collected  over  the  cistern.  One  ounce  of 
chlorate  of  potassa  will  give  about  640  cubic  inches  of  oxygen. 

Physical  Properties.  Oxygen  is  transparent,  colorless, 
tasteless,  and  inodorous.  In  the  simple  state,  it  always  exists 
in  the  form  of  a  gas.  It  cannot  be  condensed  to  a  liquid 
or  a  solid,  by  pressure  or  cold.  It  refracts  light  the  least 
of  all  substances ;  is  a  non-conductor  of  electricity ;  is  the 
only  substance  whose  electric  state  is  absolutely  negative; 
and  of  course  it  always  goes  to  the  positive  pole  in  the 
galvanic  circuit.  Its  specific  gravity  is  1.1026;  conse- 
quently, 100  cubic  inches,  when  the  thermometer  is  at  60° 
Fahr.  and  the  barometer  at  30  inches,  will  weigh  34.1872 
grains.  It  is  a  little  heavier  than  atmospheric  air. 

Chemical  Properties.  Oxygen  possesses  more  extensive 
powers  of  combination  than  any  other  substance.  It  may  be 
made  to  combine  with  all  the  simple  substances.  For  acids 
and  alkalies  it  has  little  affinity,  because  these  substances 
have  already  received  their  proportion  of  it.  Some  of  its 
combinations  with  the  metals,  and  with  combustibles,  are 
very  energetic. 

Erp.  1.  Let  down  a  pendent  candle  into  ajar  of  the  gas,  (Fig.  61,) 
and  it  will  burn  with  great  brilliancy. 


*  The  iron  retort  is  an  iron  bottle  with 
a  long  neck.  After  the  salt  or  the  man- 
ganese is  put  into  it,  it  may  be  placed 
in  a  furnace,  and  a  lead  pipe,  as  o  or  a, 
(Fig.  60,)  adapted  to  the  mouth,  by 
means  of  a  cork,  a,  a.  The  cork  is  first 
perforated  by  a  hot,  sharp  iron,  and  en- 
larged, so  as  exactly  to  fit  the  tube,  by  a 
round  file  ;  it  is  then  pressed  into  the 
mouth  of  the  bottle.  The  other  end 
may  then  be  conveyed  to  any  part  of 
the  pneumatic  cistern,  or  to  the  gas- 
ometers. This  is  the  simplest  mode  of 
connecting  apparatus  together ;  and  it 
may  be  done  either  with  glass  or  lead 
tubes. 


Fig.  GO. 


132 


Oxygen.  —  Theory. 


Fig.  62. 


Exp.  2.    Blow  out  a  candle,  leaving  a  red   wick,       Fig.  61. 
and  let  it  down  into  a  jar  of  the  gas,  when  it  will  be 
relighted  with  a  slight  explosion.     This  process  may 
be  repeated  several   times  in  rapid  succession  with 
the  same  jar  of  gas. 

Exp.  3.  If  a  bit  of  lighted  phosphorus,  in  a  capsule, 
be  immersed  in  this  gas,  (Fig.  62,)  it  will  burn  with 
great  energy  and  intense  brilliancy.  Substitute  for 
the  phosphorus  a  small  ball  formed  of  turnings  of 
zinc,  in  which  a  small  bit  of  phosphorus  is  enclosed, 
and  set  fire  to  the  ^phosphorus,  as  before.  The  zinc 
will  be  inflamed,  and  burn  with  a  beautiful  white 
light.  Metallic  arsenic,  moistened  with  spirits  of 
turpentine,  and  various  other  metals,  in  tine  powder, 
may  be  burned  in  a  similar  manner.  Homberg's 
pyrophorus  flushes  spontaneously,  like  inflamed  gun- 
powder. 

Exp.  4.  If  iron  wire,  with  a  small  lighted  match 
attached  "to  one  end,  be  let  down  into  a  tubulated 
bell  glass  of  oxygen,  it  will  burn  rapidly  ;  and  if  a 
watch-spring  be  used,  (Fig.  63,)  the  bell  glass  will 
be  filled  with  beautiful  star-shaped  scintillations. 

Exp.  5.  Or,  let  a  stream  of  oxygen  upon  ignited 
charcoal,  upon  which  is  placed  the  end  of  a  watch- 
spring  ;  it  will  burn  with  great  brilliancy,  and  throw  out 
immense  numbers  of  the  star-shaped  scintillations. 

Exp.  6.  Put  a  small  bit  of  phosphorus  into  a  test- 
glass  tube,  and  fill  the  tube  with  warm  water,  so  as  to 
melt  the  phosphorus.  Direct,  now,  a  stream  of  oxygen 
gas  from  the  gas  bag,  or  a  bladder,  to  which  a  tube 
is  attached,  upon  the  phosphorus.  A  brilliant  combus- 
tion will  be  produced  under  water. 

All  substances,  by  combustion  in  oxygen,  increase  in  in  iglit, 
in  the  proportion  of  about  £  of  a  grain  for  every  cubic  foot  ot 

Exp.  7.  Fill  the  bowl  of  a  tobacco-pipe  with  iron  wire,  coiled  in  a 
spiral  form,  and  carefully  .weighed  ;  heat  the  bowl  of  the  pipe  red  hot, 
and  then  attach  the  pipe  to  a  bladder  filled  with  oxygen  gas.  Uy 
forcing  a  stream  of  the  gas  through  the  pipe,  the  iron  will  burn,  and 
will  be  found,  when  weighed,  to  be  heavier  than  before.  When  com- 
pletely oxidized,  100  parts  of  iron  will  gain  an  addition  of  about  30. 

Theory.  In  these  experiments,  the  oxygen  combines  with 
the  combustible  substance,  and  forms  a  compound,  which, 
being  now  oxidized,  is  incapable  of  further  combustion.  In 
case  of  the  iron,  an  oxide  is  formed,  the  weight  of  which  is 
exactly  equal  to  that  of  the  iron  and  the  oxygen  together.  In 
case  of  the  phosphorus,  an  acid  is  formed,  which  is  absorbed 
by  water,  if  present,  or  appears  as  a  fine  powder.  The  heat 
and  light  appear  to  arise  from  the  condensation  of  the  .gas.* 

*  In  the  case  of  combustion,  the  common  opinion  that  the  matter  is 
destroyed,  is  erroneous.  If  the  products  are  collected,  they  will  be 
found  equal  in  weight  to  the  substances  burned.  It  is  a  universal  law 
that  no  particle  of  matter  is  annihilated. 


Chlorine.  133 

The  combination  of  oxygen  with  other  substances  is  called 
oxygcnation,  and  if  the  compound  be  an  oxide,  oxidation* 
Oxygen  is  slightly  absorbed  by  several  substances ;  100  cubic 
inches  of  water  absorb  three  or  four  cubic  inches  of  the  gas. 

The  relation  of  oxygen  to  animal  life  is  very  intimate  and 
important.  It  is  the  only  substance  which  will,  for  any  length 
of  time,  support  respiration.  No  animal  can  live  without  it. 
If  confined  in  gases  destitute  of  oxygen,  death  is  the  certain 
consequence.  A  few  years  since,  148  persons  were  confined 
in  a  prison  called  '  Black  Hole,'  in  Calcutta,  for  a  night,  and, 
although  there  were  two  windows  open  in  the  west  end  of  the 
building,  only  twenty-three  were  found  alive  in  the  morning. 

Pure  oxygen  gas  is  generally  destructive  to  animal  life. 
The  animal  confined  in  it  lives  too  fast ;  breathing  becomes 
difficult,  and  if  it  remain  for  any  time,  death  will  ensue. 

If  the  quantity  be  small,  it  will  support  life  longer  than  the 
same  quantity  of  common  air.  A  bird  will  live  five  or  six 
times  as  long  in  a  few  gallons  of  oxygen  as  in  the  same 
quantity  of  confined  air.  In  order  to  its  most  salutary 
effects,  it  should  be  diluted  with  nitrogen,  as  we  find  it  in  the 
atmosphere.  The  Creator  has,  in  this  respect,  adapted  it  to  the 
support  of  life,  as  any  thing  which  destroys  the  relation  thus 
established,  renders  it  deleterious  to  the  animal  constitution. 

Uses.  Oxygen  has  been  used  with  good  results  in  certain 
diseases,  such  as  paralysis  of  the  thorax,  and  general  debility. 
Its  effect  upon  the  blood  is  to  change  it  from  dark  red  to  a 
bright  vermilion. 

SECT.  2.     CHLORINE. 

cs      u   m       v     •     $  by  vol.  100.  o      r,     C    2.47  Air     =1. 

Symb.  Cl.      Equiv.  £    £  wgt.  35.43.       «p.  Gr.  £  ^  ^  Hyd  =1 

History.  Chlorine  was  discovered  by  Scheele  in  1774, 
and  described  under  the  name  of  dephlogisticated  marine 

*  It  has  been  customary  with  many  to  call  oxygen,  and  some  other 
kindred  substances,  "  supporters  of  combustion,"  while  the  substances 
with  which  they  combine  are  called  combustibles.  But  the  supporters  of 
combustion  and  the  combustibles  are  alike  essential  to  the  combustion, 
and  both  are  consumed  in  the  process.  Indeed,  if  the  latter  be  in  ex- 
12 


134  Chlorine.  — History. 

acid.  The  French  chemists  called  it  oxygenized  muriatic 
acid,  afterwards  contracted  to  oxy-muriatic  acid.  This  name 
implied  a  theory  of  its  composition,  suggested  by  Berthollet, 
that  it  was  a  compound  of  muriatic  acid  and  oxygen.  Gay 
Lussac  and  Thenard,  in  1809,  first  suggested  that  it  might 
be  a  simple  substance.  Sir  H.  Davy,  after  subjecting  it  to 
the  most  powerful  decomposing  agents,  without  in  the  least 
affecting  its  character,  denied  its  compound  nature,  and 
maintained  that,  according  to  the  true  logic  of  chemistry,  it 
should  be  regarded  as  a  simple  body.  The  views  of  Davy 
were  for  a  long  time  combated.  Drs.  Murray  and  Thomp- 
son in  England,  and  Berthollet,  Gay  I^ussac,  and  Thenard  in 
France,  engaged  with  great  warmth  in  the  controversy. 
But  the  name  chlorine,  suggested  by  Davy  from  a  Greek 
word*  signifying  green,  not  implying  any  theory  as  to  its 
nature,  came  gradually  into  use,  and  the  contest  subsided. 
It  is  now  universally  regarded  as  a  simple  substance. 

The  introduction  of  chlorine  into  the  class  of  simple 
bodies  changed  entirely  the  views  of  chemists  relative  to  the 
theory  of  combustion.  Previous  to  the  discovery  of  oxygen, 
the  Stahlian  theory  of  combustion  was  generally  adopted. 
According  to  this  theory,  combustion  was  the  escape  from 
combustibles  of  a  certain  principle  called  /j///w"-/>70//,  which 
pervaded  most  bodies.  Soon  after  the  discovery  of  oxyirrn, 
Lavoisier  made  an  attack  upon  the  phlogistic,  or  Stuhli.in 
theory,  and  proved  that  combustion  was  produced  by  the 
union  of  oxygen  with  some  combustible  body.  But  when  the 
properties  of  chlorine  were  investigated,  and  it  was  viewed  as 
a  simple  substance,  it  was  found  to  produce  all  the  phenomena 
of  combustion.  Hence  the  theory  of  Lavoisier,  that  combus- 
tion was  owing  to  the  union  of  oxygen  with  a  combustible,  u  us 
extended ;  and  the  phenomena  of  combustion  are  not  referred 
to  any  more  specific  cause  than  intensity  of  chemical  action. 

Natural  History.  Chlorine  is  one  of  the  constituents  of 
common  salt,  and  therefore  exists  in  the  ocean  in  large  quan- 
tity. Other  compounds  in  the  mineral  kingdom  are  numerous. 

cess,  a  portion  of  it  will  remain,  while  the  former  will  be  entirely  con- 
sumed. Generally,  the  supporter  of  combustion,  as  it  is  called,  is  a  gas 
which  envelops  the  combustible  ;  but  there  is  no  scientific  distinction. 


Physical  and  Chemical  Properties.  135 

Processes.  1.  It  may  be  obtained  in  the  form  of  a  gas,  by 
the  action  of  hydrochloric  acid  upon  the  binoxide  of  manga- 
nese. Take  the  latter,  finely  powdered,  in  a  retort,  and  pour 
on  twice  its  weight  of  concentrated  hydrochloric  acid.  Collect 
the  gas  over  the  cistern  in  inverted  bottles  containing  warm 
water,  or,  more  conveniently,  over  a  small  cistern  of  warm 
water.  The  water  should  be  raised  to  70°  or  80°  Fahr.,  as 
cold  water  japidly  absorbs  the  gas.  Apply  a  moderate  heat ; 
and,  when  the  bottles  are  filled,  they  should  be  stopped  with 
ground  glass  stoppers  smeared  with  tallow. 

Theory.  In  this  process,  the  binoxide  of  manganese  is 
decomposed  into  protoxide  and  oxygen.  A  part  of  the  acid 
combines  with  the  protoxide,  and  another  is  decomposed,  its 
hydrogen  uniting  with  the  oxygen,  and  forming  water,  and 
the  chlorine  is  set  free.  In  other  words,  the  MnO2  and  HC1 
are  converted  into  MnO +  HC1;  and  HO,  which  remain  in 
the  retort,  and  Cl,  which  comes  over. 

2.  The  cheapest  mode  of  obtaining  chlorine  is  the  follow- 
ing : —  Put  eight  ounces  of  common  salt,  with  three  ounces 
of  pulverized  peroxide  of  manganese,  and  five  ounces  of 
sulphuric  acid,  diluted  with  equal  weights  of  water,  into  a 
Florence  flask  or  retort,  and  apply  heat  as  before.  The 
MnO2,  Na  +  Cl,  and  2SO3  are  converted  into  MnO-f 
SO3,  NaO  +  SO3,  and  Cl. 

Physical  Properties.  Chlorine  gas  is  of  a  greenish-yellow 
color ;  has  an  astringent  taste,  and  a  disagreeable  odor ;  is  a 
non-conductor  of  electricity,  and  goes  to  the  positive  pole  in 
the  galvanic  circuit.  By  the  pressure  of  four  atmospheres, 
or  6;)  Ibs.  to  the  square  inch,  it  is  condensed  into  a  yellow 
liquid,  and  into  a  solid  by  the  reduction  of  the  temperature 
below  32°.*  100  cubic  inches  of  this  gas  at  60°  Fahr.,  and 
30  barometer,  w^igh  76.5988  grains. 

Chemical  Properties.  Chlorine  unites  with  many  sub- 
stances with  great  energy,  producing  combustion;  but  its 
range  of  affinity  is  more  limited  than  that  of  oxygen. 

*  Mr.  Faraday  succeeded  in  condensing  it  in  a  bent  tube,  sealed 
hermetically.  The  pressure  is  produced  by  the  accumulation  of  the  gas 
evolved  by  the  affinities  between  the  materials  in  the  short  end  of  the 
tube.  The  experiment  is  attended  with  the  hazard  of  breaking  the  tube, 
and  should  not  be  attempted,  unless  the  hands  and  face  are  protected. 


136  Chlorine. 

Exp.  1.  If  a  small  lighted  taper  be  immersed  in  a  jar  of  the  gas,  the 
taper  will  burn  for  a  short  time  with  a  small  red  flame,  evolving  large 
quantities  of  smoke,  and  then  go  out.  The  reason  is,  that  the  Rune  is 
mostly  composed  of  carbon  and  hydrogen  ;  the  chlorine  unites  \vith  the 
hydrogen,  but  not  with  the  carbon ;  the  latter  is  therefore  precipitated 
in  the  form  of  smoke,  and  soon  puts  the  light  out. 

Exp.  2.  Into  a  tall  glass  vessel,  filled  with  chlorine,  throw  finely- 
pulverized  antimony ;  the  metal  will  burn  as  it  falls  through  the  gas. 

Exp.  3.  A  rag  wet  with  oil  of  turpentine  will  instantly  be  inflamed, 
when  immersed  in  the  gas. 

Ksp.  4.  Introduce  phosphorus  into  ajar  of  chlorine;  the  phosphorus 
will  soon  ignite,  and  burn  with  a  pale-green  flame. 

Exp.  5.  Instead  of  the  phosphorus,  drop  in  a  few  drops  of  liquid 
ammonia;  the  ammonia  will  be  decomposed;  a  flash  and  a  white 
smoke  will  be  instantly  produced. 

Several  other  metals  and  combustibles  combine  with  chlo- 
rine with  such  energy  as  to  exhibit  the  phenomena  of  com- 
bustion. 

Chlorine  is  readily  absorbed  by  water.  Recently-boiled 
water,  when  cold,  absorbs  twice  its  bulk,  but  gives  it  off  when 
heated. 

Exp.  Into  a  jar  furnished  with  a  well-fitted  glass  stopper,  and  filled 
with  cold  water,  let  up  chlorine  gas  enough  to  displace  half  the  water; 
stop  it  tight,  and  shake  it,  and  most  of  the  gas  will  be  absorbed  by  the 
water.  Open  the  jar  under  more  cold  water,  which  will  rush  into  it  to 
fill  the  vacuum  occasioned  by  the  absorption  of  the  chlorine  ;  then  re- 
peat the  process  once  or  twice,  and  the  water  will  be  saturated  with 
chlorine,  and  possess  most  of  its  properties.  If  the  water  in  this  ex- 
periment be  at  the  temperature  of  32°  Fahr.,  the  chlorine  will  form  a 
definite  solid  compound  with  it,  in  yellow  crystals,  which  will  be  set  n 
on  the  sides  of  the  jar.  The  crystals  are  composed  of  35.42  or  1  atom 
of  chlorine,  and  90  or  10  atoms  of  water. 

Chlorine  forms  with  hydrogen,  if  the  vapor  of  water  be 
present,  a  mixture  which  explodes  violently  when  exposed 
to  the  direct  rays  of  the  sun,  or  even  in  a  bright  day  with- 
out such  exposure. 

Ex».  Mix,  in  a  dark  place, equal  measures  of  hydrogen  and  chlorine. 
Expose  the  mixture  to  the  light  of  day,  and  a  slow  action  will  take 
place.  Cover  the  glass  with  a  black  cloth,  to  which  a  string  is  attached, 
and  place  the  vessel  in  the  direct  rays  of  the  sun.  Remove  the  cloth 
by  means  of  the  string,  taking  care  to  have  some  object,  as  a  door,  be- 
tween you  and  the  receiver;  as  soon  as  the  rays  of  light  strike  the 
mixture,  a  violent  explosion  will  occur,  and  an  acid  compound  will 
be  formed. 

Chlorine  possesses  remarkable  bleaching  properties. 
Exp.  ].    Immerse  in  the  gas  strips  of  calico,  flowers,  etc.,  and  they 
will  be  bleached  in  a  short  time ;  or  the  saturated  water  may  be  used. 


Uses  of  Chlorine.  137 

Exp.  2.  Pour  some  of  the  saturated  water  into  a  small  quantity  of 
ink,  and  the  color  will  be  discharged;  or  put  into  it  some  writing, 
which  will  become  invisible,  but  will  be  restored  if  immersed  in  a  solu- 
tion of  prussiate  of  potassa.  Printers'  ink  will  not  be  affected ;  and 
hence  chlorine  water  may  be  used  for  removing  blots  from  books. 

Chlorine  is  not  an  acid;  for  it  does  not  redden  vegetable 
purples,  and  it  combines  directly  in  definite  proportions  with 
the  metals,  which  is  not  true  of  any  acid.  It  is  not  alkaline. 

Chlorine  is  very  destructive  to  animal  life.  A  few  bubbles 
of  gas,  in  the  atmosphere  of  a  room,  will  bring  on  coughing. 
Half  a  gill  undiluted  in  the  lungs  would  cause  death.  If 
diluted  largely  with  air,  it  irritates  the  throat  and  lungs,  and 
if  pure,  destroys  their  texture.  Pelletier  is  said  to  have  fallen 
a  victim  to  its  effects.  The  antidote  is  ammonia. 

Use*.  1.  Thf  bleaching  properties  of  chlorine  are  turned 
to  great  account  in  the  art  of  bleaching.  Both  the  gas  and 
the  water  saturated  with  it  were  employed  as  early  as  1784-5 
for  bleaching  cloths ;  but  it  proved  injurious  to  the  workmen. 
In  1789,  the  gas  was  condensed  in  a  solution  of  pearlashes, 
and  went  by  the  name  of  "  Liquid  javelle."  But  this  sub- 
stance soon  gave  place  to  Mr.  Tennant's  preparation  of  the 
chloride  of  lime,  in  1798.  Since  that  period,  most  of  the 
bleaching  of  cotton  and  linen  goods  has  been  effected  by  this 
substance.  The  articles  to  be  bleached  are  first  steeped  in  hot 
water,  boiled  in  a  weak  alkali,  and  then  immersed  in  a  solu- 
tion of  the  chloride  of  lime.  They  are  next  taken  out,  and 
washed  in  water ;  sometimes  diluted  sulphuric  acid  is  applied 
to  increase  their  whiteness;  and,  finally,  they  are  boiled  in 
pearlashes  and  soap,  to  render  them  free  from  the  odor  of 
chlorine.  Chloride  of  soda,  magnesia,  and  potassa,  are  some- 
times used,  but  they  are  more  expensive.* 

Theory.  The  theory  of  this  process,  perhaps,  would  be  better  un- 
derstood after  learning  the  composition  of  water;  but  it  can  be  given 


*  The  advantages  of  this  mode  of  bleaching,  over  the  one  formerly 
employed,  are  very  great.  By  the  old  method,  large  fields  in  the 
vicinity  of  every  manufactory  were  devoted  to  the  purpose  of  spread- 
ing- the  cloths.  These  fields  are  now  devoted  to  agriculture.  It  re- 
quired also  several  weeks,  and  even  months,  to  complete  a  process 
which  may  now  be  performed  in  as  many  days.  In  the  former  case, 
they  were  dependent  upon  the  light  of  the  sun  and  fair  weather ; 
in  the  latter,  they  are  independent  of  the  weather,  and  of  the  seasons 
of  the  year. 

12* 


138  Chlorine  and  Oxygen. 

here  with  a  little  explanation.  Water  is  necessary  to  the  bleaching 
effects  of  chlorine.  It  is  composed  of  oxygen  and  hydrogen.  The 
chlorine,  having  a  strong  affinity  for  the  hydrogen,  decomposes  the 
water,  and  leaves  the  oxygen  to  combine  with  the  coloring  matter. 
The  coloring  matter  may  also  contain  hydrogen,  and  thus  be  directly 
decomposed  by  the  chlorine.  The  coloring  matter  is  rendered  soluble 
by  combination  with  oxygen,  and  is  removed  by  the  alkali.  The  pro- 
cess of  bleaching  by  chlorine  is  but  one  out  of  many  useful  con- 
tributions of  science  to  art. 

2.  Another  use  of  chlorine  arises  from  it*  difinfrcting 
agency.  It  seizes  hold  of  every  species  of  animal  and  vege- 
table effluvia,  and  decomposes  them.  Hence  its  utility  in 
contagious  diseases.  The  chloride  of  lime  is  used  for  this 
purpose.  Moisten  the  dry  chloride  with  water,  and  place  it 
in  the  infected  apartment,  which  will  soon  be  purified.  It  is 
thus  very  useful  for  dissecting-rooms,  for  cleaning  drains, 
sewers,  vessels,  and  even  the  atmosphere,  when  charged  with 
miasma.  Its  use  in  medicine  is  mostly  confined  to  the  puri- 
fication of  apartments  of  the  sick.  The  chloride  of  sod;i  is, 
however,  used  in  certain  cases  of  inflammation,  such  as 
ulcers,  mortification,  and  cutaneous  diseases.  It  is  also  used 
as  a  wash  for  the  teeth.*  The  compounds  of  chlorine  with 
the  metals  are  called  chlorides. 


Chlorine  and  Oxygen. 
The  compounds  of  chlorine  and  oxygen  are  held  together 


by  very  feeble  affinities,  and  are  never  met  with  in 

They  cannot  be  made  to  combine  directly,  unless  they  are  in 

the  nascent  state,  that  is,  at  the  instant  of  their  formation. 

Hypochlorous  Acid.  Symb.  Cl  +  O  or  CIO.  Equiv.  35.42  -f 
8  =  43.4£  Sp.  gr.  3.0<2l2.  It  was  discovered  by  H.  Davy, 
in  1811,  and  called  euchlorine  from  its  being  of  a  brighter 
color  than  chlorine. 

Preparation.  Put  two  parts  of  the  chlorate  of  potassa  and  one  of 
hydrochloric  acid  into  a  retort,  and  apply  the  heat  of  water  under 
200°  Fahr.  Collect  over  mercury  ;  or  it  may  be  more  conveniently 
prepared  for  experiment  by  placing  the  materials  in  a  flask, 


*  So  many  and  great  are  the  advantages  of  cleanliness  and  pure  air, 
that  chloride  of  lime  should  be  kept  in  every  family,  especially  in  cities 
and  large  towns ;  but  an  apartment  in  which  it  has  been  used  should 
be  thoroughly  ventilated  before  it  is  again  occupied,  or  weak  lungs  may 
be  seriously  injured. 


Chlorine  and  Oxygen.  139 

Fig.  64. 


a,  (Fig.  64,)  connected  by  a  glass  tube,  bent  twice 
at  right  angles,  with  a  tall  receiver,  b.  Apply 
heat  as  before ;  the  gas,  being  heavier  than  the 
air.  will  displace  it,  and  fill  the  receiver. 

Theory.  The  hydrochloric  acid  and  the  chlo- 
ric acid  in  the  chlorate  of  potassa  mutually  decom- 
pose each  other,  and  the  results  are  water  and  the 
hypochlorous  acid.  2  equiv.  HC1,  and  one  of 
KG -|- CIO5,  are  converted  into  KO,  2  Aq,  and 
3C1O. 


If  the  gas  be  collected  over  mercury,  the  chlorine  unites 
with  the  mercury,  and  the  acid  remains  in  a  pure  state. 

Properties.  Greenish  yellow  color,  more  brilliant  than 
chlorine ;  odor  like  burned  sugar ;  absorbed  rapidly  by  water, 
;uid  gives  to  it  an  orange  color;  bleaches  vegetable  sub- 
stances; gives  vegetable  blues  a  red  tint  before  destroying 
them ;  does  not  unite  with  alkalies,  and  hence  has  been  con- 
sidered as  a  protoxide  of  chlorine;  highly  explosive,  the  heat 
of  the  hand  being  sufficient  often  to  explode  it.  Many  sub- 
stances take  fire  in  it  spontaneously. 

Erp.  A  rag  dipped  in  spirits  of  turpentine  will  kindle  in  it  with  a 
slight  explosipn. 

/.//>.  Phosphorus  explodes  in  it  spontaneously.  Fifty  measures  of 
this  gas,  and  eighty  of  hydrogen,  form  an  explosive  mixture. 

C' dorms  Acid.  Symb.  C1  +  4O,  or  CIO4.  Equiv.  35.42 
-f  .\l  —  67.42.  Sp.  gr.  2.3374.  Discovered  by  Davy,  in 
1815,  and  soon  after  by  Count  Stadion,  of  Vienna,  and  has 
been  heretofore  described  as  peroxide  -of  chlorine. 

Pn  partition.  Make  a  paste  of  strong  sulphuric  acid  and  chlorate  of 
potassa ;  put  it  into  a  retort,  and  apply  the  heat  of  warm  water  under 
•212°  Fahr.  Collect  over  mercury,  or  as  in  Fig.  64.  For  the  purposes 
of  experiment,  take  a  wine  or  champagne  glass,  and  put  into  it  a  few 
grains  of  chlorate  of  potassa;  then  pour  on  sulphuric  acid;  the  gas  will 
soon  fill  the  glass.  As  the  gas  often  explodes  spontaneously,  this  is  the 
safest  mode  of  collecting  it.  The  preceding  compound  may  be  formed 
in  the  same  way. 

Properties.  Color,  bright  orange-green,  richer  than  the 
preceding-  compound  ;  aromatic  odor ;  is  absorbed  rapidly  by 
water,  and  gives  it  its  peculiar  color;  bleaches  powerfully, 
and  is  more  explosive  than  hypochlorous  acid. 

Exp.  Put  a  bit  of  phosphorus  into  a  wine  glass  filled  with  the  gas. 
It  will  instantly  ignite,  with  a  slight  explosion. 

Chloric  Acid.  Symb.  Cl  -f  5O,  or  CIO5.  Equiv.  35.42  + 
40  —  75.42.  It  was  first  noticed  by  Mr.  Chenevix,  and  ob- 
tained in  a  separate  state  by  Gay  Lussac. 


140  Iodine. 

Preparation.  To  a  dilute  solution  of  chlorate  of  baryta  add  dilute 
sulphuric  acid  sufficient^  combine  with  the  baryta.  Pure  chloric  acid 
will  remain  after  the  baryta  subsides. 

Theory.  The  sulphuric  acid  has  a  stronger  affinity  for  baryta  than 
the  chloric  acid  with  which  it  has  combined,  decomposes  it,  and  leaves 
the  chloric  acid. 

Properties.  Sour  to  the  taste;  reddens  vegetable  blue 
colors,  but  possesses  no  bleaching  properties,  by  which  it  is 
distinguished  from  the  preceding  compounds.  It  may  be 
concentrated  by  gentle  heat  into  an  oily  liquid  of  a  yellow 
tint,  emitting  the  odor  of  nitric  acid.  In  this  state,  it  sets 
fire  to  paper  and  dry  organic  matter,  and  converts  alcohol 
into  acetic  acid. 

Perchloric  Acid.  Symb.  Cl  +  7O  or  CIO7.  Equiv.  35.42 
-f  56  =  91  .42.  Sp.  gr.  1  .65,  water  =  1  .  It  was  first  described 
by  Count  Stadion,  of  Vienna. 

Process.  It  may  be  obtained  by  heating  a  mixture  of  I  part  of  water, 
3  of  sulphuric  acid,  and  5  of  perchlorate  of  potassa.  At  a  teni|M-r:iiiii<' 
of  284°,  white  vapors  arise  in  the  receiver,  which  are  soon  condensed  into 
a  colorless  liquid.  By  admixture  with  sulphuric  acid,  and  distillation, 
it  crystallizes  in  elongated  prisms. 

It  is  a  very  stable  compound  ;  absorbs  moisture  from  the 
air  powerfully,  and  boils  at  392°  Fahr.  When  thrown  into 
water,  it  hisses  like  red-hot  iron. 

SECT.  3.     IODINE. 


<?  mx  1      Pm   „    fby  vol.  100.  <j     rr 

Symb.  1.    Equiv.  £  £  wgt  J26  3        Sp.  Gr. 


C  4.948  Water  =  1. 
J  g  >70g  Ajr      =1 

History.  Iodine  was  discovered  in  1812,  by  a  manu- 
facturer of  saltpetre  —  M.  Courtois,  of  Paris.  The  substance 
in  which  it  was  first  noticed,  was  the  residual  liquor  after  the 
preparation  of  soda  from  the  ashes  of  sea-weeds.  This  dark- 
colored  liquor  possessed  the  peculiar  property  of  powerfully 
corroding  metallic  vessels  ;  on  the  application  of  sulphuric 
acid,  life  noticed  that  it  threw  down  a  dark-colored  substance, 
which  was  converted  into  a  violet-colored  vapor  on  the  ap- 
plication of  heat.  This  attracted  his  attention,  and  he  gave 
some  of  it  to  M.  Clement,  who,  in  1813,  described  it  as  a 
new  body.  Gay  Lussac  and  Davy  soon  after  proved  it  to  be 
a  simple  non-metallic  substance,  analogous  to  chlorine.  The 


Physical  Properties.  141 

name  iodine  is  derived  from  a  Greek  word,*  significant  of 
the  beautiful  violet  color  of  its  vapor. 

Natural  History.  Iodine  exists  in  nature  but  in  small 
quantities.  It  is  found  mostly  in  sea-weeds,  in  sponges,  in 
the  oyster  and  some  other  mollusca,  in  many  salt  and  mineral 
springs,  both  in  Europe  and  America.  Vauquelin  found  it  in 
combination  with  silver ;  marine  animals  and  plants  derive  it 
from  sea-water.  Most  of  the  iodine  of  commerce  is  obtained 
from  the  impure  carbonate  of  soda,  called  kelp.  This  is 
nothing  but  the  ashes  of  sea-w.eed,  great  quantities  of  which 
are  prepared  on  the  shores  of  Scotland.  Iodine  exists,  in 
combination  with  sodium  and  potassium,  in  the  liquor  which 
is  left  after  the  carbonate  of  soda  crystallizes. 

Process.  Iodine  may  be  obtained  by  lixiviating  the  pow- 
dered kelp  in  cold  water.  Evaporate  the  lye  till  the  car- 
bonate of  soda  crystallizes ;  take  the  residual  liquor,  and 
evaporate  it  to  dryness ;  pour  on  to  this  J  its  weight  of  sul- 
phuric acid ;  it  may  then  be  put  into  a  common  retort,  to 
which  is  attached  a  globe  receiver,  and  the  retort  heated; 
violet-colored  fumes  will  soon  arise,  and  be  condensed  in 
the  receiver,  in  the  form  of  opaque  crystals,  of  a  metallic 
lustre.  These  are  to  be  washed  in  water,  and  dried  on  a 
filter  of  unglazed  paper. 

Physical  Properties.  Iodine,  at  the  common  temperature, 
is  a  soft,  pliable,  opaque  solid,  of  a  bluish-black  color,  and 
of  a  metallic  lustre.  It  is  generally  fouftd  in  small  crystalline 
scales,  resembling  micaceous  iron  ore,  or  the  scales  from  a 
smith's  forge.  But  it  may  be  made  to  crystallize  in  large 
rhomboidal  plates,  whose  primary  form  is  a  rhombic  octohe- 
dron,  by  saturating  hot  alcohol,  or  hydriodic  acid,  with  it, 
and  evaporating  in  the  open  air.  It  is  very  acrid  to  the, 
taste,  and  has  the  odor  of  chlorine.  Like  O  and  Cl,  it  is  a 
non-conductor  of  electricity,  and  goes  to  the  positive  pole  in 
the  galvanic  circuit.  It  acts  as  a  powerful  poison  to  the 
animal  system;  fuses  at  225°,  and  boils  at  347°  Fahr.  If 
moisture  be  present,  it  volatilizes  at  the  common  temperature, 


142  Iodine. 

and  sublimes  rapidly  under  212°.  The  rich  violet  vapor  of 
iodine  is  remarkably  dense,  more  than  eight  times  as  heavy  as 
air.  One  hundred  cubic  inches  would  weigh  269.8638  grs. 

Exp.  This  vapor  may  be  shown  by  putting  a  few  grains  of  the 
iodine  into  a  gloss  flask,  and  applying  a  gentle  heat. 

Chemical  Properties.  Iodine  has  an  extensive  range  of 
affinity.  Like  chlorine,  it  destroys  vegetable  colors,  though 
in  a  less  degree,  and,  like  oxygen  and  chlorine,  it  unites 
directly  with  the  metals  and  with  non-metallic  combustibles 
with  great  energy. 

Exp.  Drop  a  bit  of  phosphorus  upon  a  few  grains  of  iodine,  con- 
tained in  a  wine-glass,  and  it  will  be  instantly  inflamed. 

The  compounds  thus  formed  resemble  those  of  oxygen  and 
chlorine.  It  has  little  affinity  for  metallic  oxides.  It  is  not 
inflammable,  but  a  supporter  of  combustion.  The  im- 
ponderables have  no  effect  to  change  its  character,  and  hence 
it  is  regarded  as  a  simple  body.  It  is  largely  soluble  in 
alcohol,  and  but  sparingly  soluble  in  water,  requiring  seven 
thousand  times  its  weight  of  water  for  solution. 

Tests.  Starch  is  a  very  delicate  test  of  iodine.  It  gives  to  the  solu- 
tion a  deep  blue  color.  A  liquid  containing  f^v\FW  part  of  its  weight 
of  iodine,  receives  a  blue  tinge  from  a  solution  of  starch. 

Iodine  is  sometimes  adulterated  with  black  lead.  This  may  be  de- 
tached by  dissolving  it  in  alcohol,  when  the  lead  will  not  be  held  in 
solution. 

Uses.  Used  in  medicine  in  the  form  of  a  hydriodate  of 
potassa,  for  certain  glandular  diseases.  The  goitre  is  a  kind 
of  wen  growing  from  the  neck*  which  is  very  common  in 
Switzerland,  in  the  treatment  of  which  iodine  has  been  of 
great  service. 

Its  vapor  is  irritating  to  the  lungs,  and  produces  copious 
secretions  in  the  eyes  and  nostrils.  The  compounds  of 
iodine  with  non-metallic  combustibles  are  termed  iodurcts  ; 
its  compounds  with  the  metals,  iodides. 

Iodine  forms  with  oxygen  three,  perhaps  four  compounds  : 


3.  lodic  acid,  1  eq.  1,  126.3  +  5  eq.  O,  40=166.3  eq. 
Symb.  I  +  5O  or  lO*. 

4.  Periodic  acid,  1  eq.  I,  126.3  +  7  eq.  O,  56=182.3. 
Symb.  I  +  7O  or  IO7. 


Bromine.  143 

The  first  two  compounds,  oxide  of  iodine  and  iodous  acid, 
are  yet  doubtful.  The  first  is  described  by  M.  Sementini,  of 
Naples,  and  the  second  by  Mitscherlich.  The  oxide  is  a 
yellow  solid,  and  the  acid  a  similar  liquid,  but  their  properties 
have  not  been  examined. 

lodic  Acid  was  discovered  by  Davy  and  Gay  Lussac  about 
the  same  time.  Davy,  who  first  obtained  it  in  a  pure  state, 
called  it  oziodine. 

Preparation.  When  iodine  is  brought  in  contact  with  the  hypochlo- 
roua  acid,  two  compounds  are  formed.  The  one  is  a  volatile  orange- 
colored  substance,  chloride  of  iodine,  and  the  other  a  white  solid,  which 
is  iodic  acid.  Apply  heat  to  expel  the  chloride,  and  the  iodic  acid  re- 
mains in  a  pure  state.  (See  Turner,  for  other  processes.)  In  this 
statr,  it  is  anhydrous  iodic  acid,  that  is,  destitute  of  water. 

Properties.  It  exists  as  a  white,  semi-transparent,  crystal- 
line solid,  of  a  strong,  astringent,  sour  taste,  and  no  odor; 
fuses  at  500°  Fahr.,  and  is  resolved  into  oxygen  and  iodine. 

It  is  soluble  in  water,  with  which  it  combines,  and  forms 
hydrous  iodic  acid  ;  deliquesces  in  moist  air  ;  reddens  vege- 
table blues,  and  finally  destroys  them.  With  charcoal,  sul- 
phur, sugar,  and  similar  combustibles,  it  forms  detonating 
mixtures. 

Periodic,  Acid  was  discovered  by  Ammermuller  and  Mag- 
nus, and  is  obtained  from  the  periodate  of  silver,  by  adding 
cold  water.  It  has  decided  acid  properties,  and  is  analogous 
in  composition  to  perchloric  acid. 

Chloriodic  Acid  was  discovered  by  Davy  and  Gay  Lussac. 
It  may  be  formed  by  the  direct  union  of  chlorine  and  iodine. 
If  the  iodine  is  fully  saturated  with  chlorine,  it  forms  a  yellow 
solid  ;  but  if  the  iodine  is  in  excess,  the  color  is  a  reddish 
orange.  It  is  easily  fused,  and  converted  into  vapor  ;  deli- 
quesces in  the  air  ;  forms  a  colorless  solution  in  water  ;  very 
sour  to  the  taste  ;  reddens  vegetable  blues,  and  finally  de- 
stroys them;  does  not  unite  with  alkalies,  and  hence  has 
been  considered  a  chloride  of  iodine. 

Souberaine  has  lately  distinguished  a  compound  of  3  eq. 
of  chlorine  and  1  of  iodine. 


SECT.  4.     BROMINE. 

8,-nb.n,  E, 


History.     Bromine  was  discovered  in  1826,  by  M.  Balard, 
a  young  French  chemist,  of  Montpellier,  who  named  \tmuride, 


144  Bromine. 

because  obtained  from  the  sea ;  but,  in  order  to  correspond 
with  chlorine  and  iodine,  it  was  called  bromine,  from  a  Greek 
word,*  signifying  rank  odor. 

Natural  History.  It  exists  in  nature  in  very  small  quan- 
tities. It  is  found  in  sea-water  and  marine  plants,  combined 
with  sodium  and  magnesium.  It  is  found  in  every  sea  whose 
waters  have  been  tested  for  it,  and  in  many  mineral  and  salt 
springs. 

Process.  It  is  obtained  by  passing  a  current  of  chlorine 
gas  through  the  bittern  of  sea-water,  and  agitating  the  liquor 
with  a  portion  of  sulphuric  ether.  The  ether  dissolves  the 
bromine,  from  which  it  receives  a  beautiful  hyacinth-red  tint, 
and,  on  standing,  rises  to  the  surface.  Agitate  this  solution 
with  caustic  potassa,  and  the  bromide  of  potassium  and  bro- 
mate  of  potassa  will  be  formed.  Evaporate  the  liquor,  and 
the  bromide  of  potassium  will  be  left,  from  which  the  bromine 
may  be  distilled. 

Physical  Properties.  Bromine,  at  common  temperatures, 
is  a  deep  reddish-brown  colored  liquor,  of  a  disagreeable  odor 
and  caustic  taste;  and,  like  oxygen,  chlorine,  and  iodine,  is  a 
non-conductor  of  electricity,  and  a  negative  electric  ;  boils' at 
116.5°  Fahr.,  and  congeals  at  -4°  Fahr.  into  a  brittle  solid. 
It  volatilizes  at  the  common  temperature  and  pressure. 

Exp.  This  may  be  shown  by  pouring  a  few  drops  of  the  liquid  into 
a  glass  flask;  it  will  soon  be  converted  into  a  beautiful  vapor,  some- 
what resembling  the  vapor  of  iodine,  having  a  density  of  5.54.  100 
cubic  inches  at  00°  Fahr.  should  weigh  167.5158  grains. 

Chemical  Properties.  Its  chemical  properties  are  very 
analogous  to  those  of  chlorine  and  iodine.  It  readily  bleaches 
litmus  paper,  and  discharges  the  blue  color  of  indigo.  A 
lighted  taper  burns  for  a  few  moments  in  the  vapor  of  bro- 
mine, with  a  flame  green  at  its  base  and  red  at  the  top,  and 
is  then  extinguished. 

Bromine  unites  with  great  energy  with  many  combustibles. 

Exp.  Pour  a  few  drops  of  bromine  into  a  strong  wine-glass,  and  then 
pour  upon  it  tin  or  antimony,  in  fine  powder,  from  a  glass  fastened  to 


Fluorine.  145 

the  end  of  a  long  rod  ;  the  metals  will  be  instantly  inflamed.     If  potas- 
sium be  used,  it  will  cause  a  violent  explosion. 

Bromine  is  soluble  in  water,  alcohol,  and  ether ;  the  latter 
is  the  best  solvent.  With  water  at  32°  F.,  it  forms  a  hydrate, 
in  crystals  of  a  fine  red  color.  It  gives  to  a  solution  of  starch 
an  orange  color.  Chlorine  will  displace  it  from  all  its  com- 
binations with  hydrogen.  It  acts  powerfully  upon  the  animal 
system,  and  is  very  poisonous ;  a  single  drop  upon  the  beak 
of  a  bird,  destroys  it  instantly. 

Bromic  Acid  (Symb.  Br-f-50  or  BrO5.  Equiv.  78.4 -f- 
40  =  118.4,)  may  be  obtained  by  pouring  sulphuric  acid 
upon  a  dilute  solution  of  bromate  of  baryta,  and  evaporating 
the  solution. 

Properties.  It  has  scarcely  any  odor,  acrid  to  the  taste, 
though  not  corrosive.  It  first  reddens  litmus  paper,  and  then 
destroys  the  color. 

Chloride  of  Bromine  may  be  formed  by  transmitting  a  current  of 
chlorine  through  bromine,  and  condensing  the  disengaged  vapors  by 
a  freezing  mixture.  It  is  a  volatile  liquid,  of  a  reddish-yellow  color, 
less  brilliant  than  bromine.  Its  vapor  is  a  deep  yellow,  taste  very  dis- 
agreeable, and  odor  penetrating,  causing  a  discharge  of  tears  from  the 
eyes.  Soluble  in  water  which  possesses  bleaching  properties. 

Bromides  of  Iodine.  Bromine  and  iodine  unite  and  form  two  com- 
pounds. 

Tlu>  prnto-lromide  is  a  solid  easily  converted  by  heat  into  a  reddish- 
brown  vapor,  which,  on  cooling,  is  condensed  into  crystals  of  the  same 
color,  and  of  a  form  resembling  fern  leaves.  By  the  addition  of  bro- 
mine to  these  crystals,  they  are  converted  into  a  liquid  resembling  a 
strong  solution  of  iodine  and  hydriodic  acid;  but  the  nature  of  it  is  not 
satisfactorily  established. 


SECT.  5.     FLUORINE. 

Symb.  F,      Equiv.  18.68,  eq.  vol.  100. 

Fluorine  is  a  name  applied  to  a  substance  which  has  not 
as  yet  been  obtained  in  a  simple  state.  It  is  inferred  from 
the  nature  of  its  compounds  to  be  similar  to  oxygen,  chlorine, 
bromine,  and  iodine.  It  has  a  strong  affinity  for  hydrogen 
and  the  metals.  . 

Natural  History.     It  exists  abundantly  in  nature,  in  fluor- 
spar combined  with  calcium,  (fluoride  of  calcium.)     Baudri- 
13 


140 


Hydrogen. 


mont  is  said  to  have  obtained  it,  mixed  with  hydrofluoric  and 
fluosilicic  acid  gases,  by  treating  a  mixture  of  fluoride  of  cal- 
cium and  peroxide  of  manganese  with  strong  sulphuric  acid. 
It  appears  to  be  a  gaseous  body,  similar  to  chlorine. 


SECT.  6.     HYDROGEN. 


Symb.  H. 


C  0.0689  Air 
Jl.          Hyd. 


History.  The  name  hydrogen  is  formed  from  two  Greek 
words,*  and  means  a  generator  of  water.  It  was  known  for 
many  centuries,  but  was  first  distinctly  described  by  Mr.  Cuv- 
endish,  in  1776.  Nine  years  previous,  Dr.  Black  discovered 
carbonic  acid  gas,  which  was  the  first  gas  discovered,  except 
the  atmosphere,  and  hydrogen  was  the  second. 

Natural  History.  Hydrogen  is  a  very  abundant  substance. 
It  forms  £  part  by  weight  of  water.  Its  chief  repository, 
therefore,  is  the  ocean ;  but  it  is  widely  disseminated  through 
the  animal,  vegetable,  and  mineral  kingdoms.  It  ij 
of  most  liquids. 

Processes.  1.  Water  is  always  employed  for  obtaining 
hydrogen.  It  is  composed  of  oxygen  and  hydrogen,  and  the 
object  is  to  decompose  it  by  presenting  some  substance,  with 
which  the  oxygen  will  combine,  and  leave  the  hydrogen  to 
escape  in  the  form  of  a  gas.  Iron  is  such  a  substance,  and 
will  decompose  the  water  slowly  at  common  temperatures ; 
the  oxygen  combining  with  it,  and  forming  the  well-known 
substance  called  iron  rust.  But  if  the  temperature  of  the  iron 
be  raised  to  1000° 

Fahr.,  and  the  va-  Fig.  65 

por  of  water  passed 
over  it,  it  will  de- 
compose it  more 
rapidly.  For  this 
purpose,  clean  iron 
turnings,  or  bright 
iron  wire,  are  pla- 
ced in  the  centre 


and 


Processes —  Theory,  147 

of  a  gun-barrel,  C,  (Fig.  65,)  open  at  both  ends,  and  passed 
through  a  furnace,  b.  Into  one  end  the  vapor  bf  water  is 
made  to  pass  from  the  retort  a,  and  the  other  end  is  con- 
nected by  a  lead  pipe  with  the  pneumatic  cistern.  As  the 
v;ipor  passes  over  the  iron,  its  oxygen  combines  with  it,  and 
its  hydrogen  passes  over  into  the  receiver  A.* 

~.  It  is  more  conveniently  obtained  by  putting  small 
pieces  of  zinc,t  or  iron  turnings,  into  a  glass  or  lead  retort, 
and  pouring  on  one  part  of  sulphuric  acid,  diluted  with  four 
pirts  by  weight  of  water,  and  collecting  as  above. 

Theory.  In  this  process,  the  oxygen  of  the  water  unites 
with  the  zinc,  and  forms  oxide  of  zinc,  which  combines  with 
the  acid,  while  the  hydrogen  of  the  water  escapes.  This  was 
formerly  supposed  to  be  a  case  of  what  was  called  disposing 
affinity,  in  which  the  acid  disposed  the  oxygen  and  zinc  to 
unite,  that  it  might  combine  with  the  compound ;  for  it  has 
no  affinity  for  them  separately.  This  is  sufficiently  absurd. 
The  process  commences  with  zinc  and  water  alone,  without 
the  aid  of  the  acid,  and  is  immediately  arrested  by  the  forma- 
tion of  a  coat  of  oxide  of  zinc,  which  protects  the  zinc  from 
the  action  of  the  water.  The  acid  dissolves  away  this  coat- 
ing of  oxide  as  fast  as  formed,  and  thus  the  action  of  the 
metal  and  the  water  is  uninterrupted. 

For  every  nine  grains  of  water  which  are  decomposed,  one 
grain  of  hydrogen  will  be  set  free.  Eight  grains  of  oxygen 
will  unite  with  twenty-eight  of  iron,  forming  thirty-six  of  the 
protoxide  of  iron.  One  ounce  of  iron  will  yield  782  cubic 
inches,  and  one  ounce  of  zinc  676  cubic  inches  of  hydrogen. 

Impurities.  The  hydrogen,  obtained  in  these  processes,  is  not  quite 
pure.  That  from  the  iron  contains  a  volatile  oil,  produced  by  the  hy- 
drogen and  the  carbon  in  the  iron;  this  may  be  removed  by  passing 
the  gas  through  alcohol.  When  zinc  is  employed,  (and  it  is  generally 


*  If  the  water  and  the  iron  are  weighed  before  the  experiment,  and 
the  iron  and  the  hydrogen  after  it—the  increase  in  the  weight  of  iron 
and  the  weight  of  the  hydrogen  is  just  equal  to  that  of  the  water. 
Jn  this  way  the"  exact  composition  of  water  is  determined  analytically, 
and  is  found  to  be  8  parts  of  oxygen  to  1  of  hydrogen,  and  1  vol.  of  the 
former  to  2  of  the  latter. 

t  The  zinc  may  be  conveniently  prepared  by  pouring  a  stream  of  the 
melted  metal  into  cold  water. 


148 


Hydrogen.  —  Physical  Properties. 


preferred,)  the  impurities  result  from  the  sulphur  which  it  generally 
contains  —  hydrosulphuric  acid  is  formed,  and  there  are  also  traces  of 
metallic  zinc  and  carbureted  hydrogen.  These,  except  the  last,  may 
be  removed  by  passing  the  hydrogen  through  pure  potassa.  VYhvn 
hydrogen  of  great  purity  is  required^  distilled  zinc  should  be  used. 

Physical  Properties.  Hydrogen  gas  is  colorless,  tasteless, 
and,  when  perfectly  pure,  inodorous.  -  But  as  it  is  generally 
obtained,  it  has  a  fetid  odor,  arising  from  the  oily  matter 
which  it  contains,  and  the  hydrosulphuric  acid.  It  is  a  pow- 
erful refractor  of  light,  and  has  never  been  condensed  to  a 
liquid. 

It  is  the  lightest  body  in  nature.  It  is  sixteen  times  lighter 
than  oxygen,  36  times  lighter  than  chlorine,  200,000  times 


mercury,   and    300  000    times 


lighter 


than 


Tig.  66. 


lighter    than 
platinum  \ 

Exp.  Fill  a  gas  bag  with 
hydrogen,*  (Fig.  66;)  con- 
nect it  with  a  bubble-pipe, 
and  inflate  soap  bubbles  with 
the  gas;  they  will  ascend 
rapidly,  being  forced  up  by 
the  superior  weight  of  the 
air.  Or,  if  a  jar  of  hydrogen 
be  removed  from  the  cistern, 
and  inverted  in  the  open  air, 
the  gas  will  immediately  escape. 

In  consequence  of  its  extreme  lightness,  hydrogen  is  used 
for  filling  balloons. 


*  The  method  of  filling  gas  bags  with 
gases  from  the  pneumatic  cistern,  is  repre- 
sented in  Fig.  67.  b  is  the  cistern  contain- 
ing water ;  the  receiver  has  a  stop-cock  in 
its  top,  upon  which  another  stop-cock,  C, 
connected  with  the  bag  a,  may  be  screw- 
ed. The  receiver  is  filled  with  gas,  and, 
the  stop-cocks  being  both  open,  is  pressed 
down  into  the  well,  and  the  water  presses 
the  gas  into  the  bag.  Then,  by  closing 
both  stop-cocks,  the  bag  may  be  removed 
from  the  receiver. 


Fig.  67. 


Chemical  Properties. 


149 


Aerostation.  Roger  Bacon  first  suggested  the  pos-  Fig.  08. 
sibility  of  navigating  the  air  by  mechanical  contri- 
vances; but  nothing  of  consequence  was  effected  until 
17d2.  The  substance  first  employed  to  raise  balloons 
was  rarefied  air,  confined  in  a  silk  bag.  Since  the 
discovery  of  hydrogen,  it  has  been  universally  cm- 
ployed  for  this  purpose.  Balloons  are  made  of  various 
hh;i[>rs  and  capacities.  The  spherical  form  (Fig.  68) 
is  the  best,  for  the  reason  that  a  given  quantity  of  can- 
vass, or  silk,  made  in  the  form  of  a  sphere,  will  contain 
more  than  any  other  form,  and  hence  offers  the  least 
resistance  to  the  air.  The  substance  employed  for  bal- 
loons is  either  varnished  silk  or  gold-beaters'  skin,  and 
the  size  varies  from  1  to  40  feet  in  diameter.  They 
are  generally  covered  with  a  net,  n,  connected  by  cords  to  &  small  boat, 
c,  in  which  the  aeronaut  i«  stationed  when  he  ascends.  The  hydrogen 
is  prepared  by  putting  iron  turnings,  sulphuric  acid,  and  water,  into 
several  large  casks,  and  connecting  each  with  the  balloon  ;  the  hydrogen 
is  then  rnpidly  evolved,  and  the  balloon  tied  down  until  ready  for  use. 

Chemifcd  Properties.  Hydrogen  has  a  strong  affinity  for 
many  substances,  and  the  energy  of  its  combinations  fre- 
quently produces  the  phenomena  of  combustion. 

Hydrogen  is  a  combustible  body,  but  not  a  supporter  of 
combustion. 

Exp.   Plunge  a  lighted  taper  into  an  inverted  jar  of  hy-     Fig.  69. 

drrvren  ;  the  gas  will  instantly  be  inflamed  at  the  mouth  of 
tiie  jar,  and  burn  with  a  blue  light;  but  the  taper,  if  wholly 
immersed  in  the  gas,  will  be  extinguished,  and  relighted 
u<r;iin  when  the  wick  touches  the  flame. 

Ejcp.  Burn  a  jet  of  hydrogen.  If  the  hydrogen  be 
forced  rapidly  through  a  tube,  i,  (Fig.  69,)  with  a  small 
orifice,  ignited  at  the  orifice,  and  cylinders  of  glass,  as  a,  or 
other  substances,  put  over  the  flame,  musical  tones  will  be 
produced.  The  tones  will  vary  with  the  size  and  kind  of 
tube. 

Exp.  Mix  two  measures  of  hydrogen  with  one  of  oxy- 
gen, and  apply  the  flame  of  a  candle  to  a  sma.U  portion 
confined  in  an  exploding  tube,  or  gas  pistol,  a,  (Fig.  70;) 
there  will  be  a  violent  explosion.  This  effect  is  also  pro- 
duced by  mixing  one  part  of  hydrogen  with  three  of  com- 
mon air;  but  the  explosions  are  much  more  violent- when 
two  vols.  of  hydrogen  and  one  of  oxygen  are  mixed,  and 
ignited  with  the  flame  of  a  candle  ;  or  by  the  electric 
spark.  Soap-bubbles  may  be  formed  and  exploded  as  they 
rise.  A  large  bladder,  filled  with  the  mixture,  may  also  be 
exploded  by  piercing  it  with  a  sharp  wire  on  the  end  of  a 
long  rod,  having  about  it  ignited  tow. 

Exp.  This  mixture  also  explodes  when  suddenly  com- 
pressed by  the  fire-syringe  ;'  this  is  owing  to  the  develop- 
ment of  its  latent  caloric,  or  because  the  particles  are  then 
brought  within  the  sphere  of  each  other's  attraction;  but 
the  experiment  is  hazardous. 

13* 


Fig.  70. 


150  Hydrogen  and  Oxygen. 

Theory.  In  these  experiments,  the  report  arises  from  the 
collapse  of  the  air,  a  vacuum  being  formed  by  the  sudden 
condensation  of  the  gases.  The  musical  tones  arise  from 
continued  explosions  produced  by  the  union  of  the  hydrogen 
and  the  oxygen  of  the  air. 

Exp.  IVhcn  a  stream  of  hydrogen  gas  is  brought  in  contact  ?r/V/i 
spongy  platinum,  it  is  immediately  set  on  fire.  This  heat  is  supposed  to 
be  due  to  the  condensation  of  the  gas  upon  the  surface  of  the  plati- 
num, by  which  its  latent  caloric  becomes  sensible,  and  inflames  the  gas. 

This  singular  fact  was  discovered  by  Prof.  Doebereiner,  of 
Jena,  in  1824.  The  sponge  is  prepared  by  dissolving  plati- 
num in  nitro-muriatic  acid,  and  then  precipitatincr  it  with 
ammonia.  Rhodium  and  iridium  produce  the  same  eiVcrt. 
This  property  has  been  applied  to  the  construction  of  lamps, 
by  which  light  can  be  easily  and  conveniently  produced. 

Under  pressure,  the  combustion  of  hydrogen  produces  a  very 
intense  heat. 

Exp.   Burn  a  jet  of  hydrogen,  and  throw  on  iron  filings ;  they  \\  ill  U- 
ignited,  and  produce  beautiful  scintillations.     One  pound  of  hy th- 
in burning,  will  develop  sufficient  heat,  according  to  Dalton,  to  melt 
320  Ibs.  of  ice. 

Relations  to  Animals.  An  animal  soon  dies  when  confined 
in  it.  This  is  not  owing  to  the  noxious  properties  of  the 
hydrogen,  since  an  atmosphere  of  oxygen  and  hydrogen  will 
support  respiration  for  a  considerable  time ;  but  is  due  to  the 
fact,  that  it  excludes  the  oxygen,  and  thus  suffocates.  An 
atmosphere  of  oxygen  and  hydrogen  has  the  singular  property 
of  producing  a  most  profound  sleep. 

Hydrogen  and  Oxygen. 

Protoxide  of  Hydrogen,  or  Water.  1  eq.  H  1  -[-  1  eq.  O  8 
=•9  eq.  Symb.  H  -f-  O  or  Aq.  Sp.  gr.  =  1. 

Process.  Water  is  the  sole  product  of  the  combustion  of 
hydrogen  gas  in  common  air,  or  oxygen.  This  may  be  shown 
by  burning  a  jet  of  hydrogen  in  a  large  globe  receiver;  or, 
what  will  render  the  effect  more  striking,  by  burning  a  jet  of 
2  vols.  of  hydrogen  to  1  of  oxygen,  with  the  compound 
blowpipe :  the  sides  of  the  receiver  will  soon  become  hazy, 
from  tne  deposition  of  water  upon  its  interior  surface ;  and  if 
the  process  be  continued,  large  drops  will  form  and  run  down 
the  sides.  This  fact  was  first  demonstrated  by  Mr.  Caven- 


Physical  and  Chemical  Properties.  151 

dish,  by  burning  the  gases  as  above  ;  and  the  weight  of  the 
water  produced  was  exactly  equal  to  that  of  the  gases  con- 
sumed. 

Physical  Properties.  These  are  well  known.  It  is  trans- 
parent, colorless,  inodorous,  and  tasteless;  slightly  com- 
pressible by  a  very  strong  pressure  ;  elastic  ;  converted  into 
vapor  by  heat  ;  boils  at  212°  F.,  and  congeals  at  32°  F.  It  is 
the  standard  of  weight,  with  which  all  sofid  and  liquid  bodies 
are  compared  ;  its  specific  gravity  is  therefore  1.  One  cubic 
inch  weighs  252.458  grs.  It  is  815  times  heavier  than  the 
atmosphere,  which  is  the  standard  of  weight  for  gaseous 
bodies. 

Chemical  Properties.  1.  Water  has  the  power  of  ab- 
sorbing a  great  number  of  gaseous  bodies.  It  always  con- 
tains air. 

Exp.  This  may  be  shown  by  placing  it  under  the  receiver  of  an  air- 
pump,  and  exhausting  the  air,  when  bubbles  of  air  will  rise  up  througtf 
the  water. 

It  is  the  air  contained  in  water  from  which  fishes  obtain 
the  oxygen  necessary  to  purify  their  blood. 

At  the  mean  temperature  and  pressure,  water  will  absorb, 
according  to  Henry  and  Dalton,  of 


Carbonic  acid  gas,    .     1  vol. 


Sulphuretcd  hydrogen,   1    "       Carbureted  hydrogen, 


Nitrous  acid,  •...! 


Carbonic  oxide,       .     ^  vol. 


Nitrogen, 


Olenant  gaa^    .     ,     .     |    "       Hydrogen,      ...      "    " 
Oxygen,       .     .     .     .    ^  "     I 

But  if  the  gas  be  passed  through  the  water  under  great 
pressure,  a  greater  quantity  will  be  absorbed.  Carbonic  acid 
gas,  for  example,  is  absorbed  according  to  the  pressure  ap- 
plied, to  an  unlimited  extent. 

2.  Water  is  one  of  the  most  pmcerful  solvents  in  nature. 
It  enters  into  combination  with  various  bodies  ;  sometimes  in 
indefinite  proportions,  as  in  solutions  ;  at  others  in  definite  pro- 
portions, as  in  the  acids,  some  of  the  metallic  oxides,  and  many 
salts,  in  whose  crystallization  it  is  taken  up,  and  in  which  it 
is  therefore  called  the  water  of  crystallization.  The  definite 


152  Hydrogen  and  Oxygen. 

compounds  are  called  hydrates*  The  affinity  of  water  for 
some  substances  is  so  strong,  that  it  cannot  be  entirely 
separated  from  them  without-s$.  the  same  time  decomposing 
the  substance. 

Composition  of  Water.     This  has  been  Fig.  71. 

accurately   determined,    both  by    analysis 
and  synthesis.     By  synthesis,  by  burning     r  L 

2  vols.  of  hydrogen  and  1  of  oxygen,  the  £_ 
product  is  water.  Also,  by  exploding  2 
vols.  of  hydrogen  and  one  of  oxygen,  in  a 
strong  glass  tube,  or  Eudiometer,  o,  (Fig. 
71,)  over  mercury,  by  the  electric  spark, 
there  will  be  a  perfect  vacuum  produced, 
and  the  mercury  will  rise,  and  fill  the  tube. 
Instead  of  inflaming  the  gases  by  the 
electric  spark,  spongy  platinum  may  be 
employed  to  produce  a  combination  of 
the  oxygen  and  hydrogen. 

Erp.  Take  three  parts  of  spongy  platinum,  one  of  pipe-play, 
moistened  with  water,  and  a  small  quantity  of  hydrochlorate  of  am- 
monia, make  it  into  a  small  ball,  and  ignite  it,  to  separate  the  water 
and  ammonia.  Introduce  it,  while  hot,  into  the  mixture,  and  the 
oxygen  and  hydrogen  will  combine  slowly,  without  explosion.  If  the 
guees  are  mixed  in  the  proportions  of  1  vol.  of  oxygen  to  2  of  hy- 
drogen, they  will  wholly  disappear,  and  water  will  be  the  only  product. 

Water  may  be  decomposed  by  the  galvanic  battery,  and  the 
products  are  2  vols.  of  hydrogen  to  1  of  oxygen.  The  same 
results  are  obtained  by  passing  its  vapor  over  red-hot  iron, 
and  collecting  the  products. 

Compound  Blowpipe.  This  apparatus  was  infented  by  Dr. 
Hare,  in  1804.  The  best  construction  for  experimental  pur- 
poses is  the  following :  A,B,  (Fig.  72,)  are  two  cylinders  of 
wood  or  copper  open  at  the  top;  c,  d,  t\vo  similar  cylinders 
open  at  the  bottom,  placed  within  the  others,  leaving  spaces 
of  J  of  an  inch  in  width  between  them,  and  passing  around 
cylinders  of  wood  which  nearly  fill  them.  The  spaces  ?,  e ,  are 
filled  with  water,  and  the  gases  are  conducted  by  a  lead  pipe 
into  c  and  d,  which  are  the  gasometers.  As  they  are  filled, 
they  are  lifted  up  by  the  weights.t  The  tubes  h,  o,  connect 

*  The  term  hydrous  is  prefixed  to  substances  containing  water,  and 
anhydrous  to  those  deprived  of  it. 

t  A  method  for  raising  and  depressing  the  gasometers  has  lately 
been  devised,  which  answers  a  better  purpose  than  weights.  A  bar  or 


Hydrogen  and  Oxygen. 
Fig.  72. 


153 


the  gasometers  with  the  blowpipe ;  the  gases  are  let  out  by 
means  of  stop-cocks,  d,  being  filled  with  oxygen,  the  gas 
passes  in  the  tube  o  through  the  centre  of  the  blowpipe ;  c, 
at  the  same  time,  being  filled  with  hydrogen,  the  gas  passes  in 
the  tube  h  to  the  side  of  the  blowpipe,  and  issues  at  the 
point,  so  as  to  encircle  the  oxygen.  By  igniting  the  two 
gases,  as  they  issue  from  the  pipe,  the  heat  is  so  intense  as  to 
melt  the  most  refractory  substances.  It  is  only  surpassed  by 
that  from  a  powerful  galvanic  battery.  In  burning  the  metals 
under  the  blowpipe,  an  opportunity  is  afforded  for  many  in- 
teresting and  beautiful  experiments.* 

ttinox'ulr  of  [lydrofffn.  Sy  mb.  H  -|- 2O or  HO2.  Equi v  1  -f- 1 6  =  1 7. 
Sp.  gr.  1  452,  water  =  1.  This  singular  compound  was  discovered  by 
Thenard  in  l^IS.  and  is  sometimes  called  oxygenized  water,  and  peroxide 
of  hydrogen.  It  is  formed  by  the  action  of  hydrochloric  acid  upon  the 
peroxide  of  barium. 

Prttficrtf.es.  The  binoxide  of  hydrogen  is  a  colorless,  transparent 
liquid,  without  odor,  caustic  to  the  skin,  giving  it  a  white  stain,  and 
possesses  powerful  bleaching  properties.  When  heated  to  5f)°  Fahr., 
it  is  decomposed  so  rapidly  as  to  cause  explosion;  the  same  effect  is 
also  produced  by  throwing  it  on  to  several  of  the  oxides  of  metals, 
such  as  the  peroxide  of  silver,  lead,  mercury,  gold,  and  some  others. 

rod  of  iron  is  fastened  by  one  end  to  the  centre  of  the  gasometers. 
The  other  end  passes  up  through  the  cross-bar  S  ;  on  one  side  of  this 
bar  are  teeth,  which  lit  into  a  cog-wheel,  and  the  gasometers  are  raised 
and  lowered  by  a  crank  attached  to  the  wheel. 

*  In  experiments  with  the  blowpipe,  the  hydrogen  should  first  be 
inflamed,  and  then  the  oxygen  let  out  gradually,  until  the  substance  to 
be  melted  is  fully  ignited;  the  hydrogen  may  then  be  shut  off,  and  the 
combustion  kept  up  by  oxygen  alone. 


154  Hydrogen  and  Chlorine. 

Hydrogen  and  Chlorine  —  Hydrochloric  Acid. 

Symb.  H  +  C1.  Eq.  by  vol.  200,  by  wgt.  35.42  +  1  = 
36.42.  Sp.  gr.  18.21  Hyd.  =  1,.  1.2694  air  =  1. 

History.  This  compound  has  been  long  known  under  the 
names  of  spirit  of  salt,  and  muriatic  arid ;  but  was  dis- 
covered in  its  gaseous  state  by  Dr.  Priestley,  in  1772. 

Natural  History.  It  issues  from  the  craters  of  volcanoes, 
and  is  found  in  the  warm  springs  of  Mexico ;  it  exists  in  com- 
bination with  ammonia,  (the  hydrochlorate  of  ammonia.) 

Process.  1.  It  can  be  obtained  in  the  gaseous  state,  by 
simply  heating  the  common  hydrous  hydrochloric  acid  of 
commerce  in  a  glass  flask,  or  retort,  and  collecting  the  gas 
over  mercury. 

2.  Put  equal  parts  of  common  salt  and  sulphuric  acid  into 
a  retort,  and  collect  as  above. 

Theory .  Salt  is  a  chloride  of  sodium,  and  sulphuric  acid  is  com- 
posed of  real  acid  and  water ;  the  oxygen  of  the  water  goes  to  the 
sodium,  and  forms  soda,  which  unites  with  the  acid,  and  the  hydrogen 
of  the  water  unites  with  the  chlorine,  forming  hydrochloric  acid.  Pfa 
4-  Cl,  SO3  and  HO,  are  converted  into  NaO-f  SO3  and  HCL 

Instead  of  collecting  the  gas  over  mercury,  it  may  be  col- 
lected in  large  vials  or  bottles,  in  the  following  manner  :  — 

Put  the  materials  into  a  flask,  a,  (see  Fig.  64,)  and  connect 
the  flask  with  a  glass  tube,  bent  twice  at  right  angles,  and 
extending  to  the  bottom  of  a  bottle  or  receiver,  b ;  as  the  gas  is 
heavier  than  the  atmosphere,  it  will  expe.1  it,  and  fill  the  bottle. 
By  the  application  of  ammonia  to  the  mouth  of  the  bottle,  a 
white  cloud  will  arise  when  the  bottle  is  filled.* 

Liquid  Hydrochloric  Arid.  This  is  obtained  in  the  arts 
by  passing  the  gas  through  water ;  for  this  purpose  Woulfe's 
apparatus  may  be  employed. 

It  consists  of  several  bottles,  b,  e,  d,  r,  (Fig.  73.)  The  first 
bottle  is  connected,  by  a  lead  tube,  with  a  glass  retort,  a,  which 
contains  the  materials ;  b  is  one  third  filled  with  water ;  the 
tube  from  6  descends  to  the  bottom  of  c,  and  the  gas  passrs 
up  through  the  water.  As  soon  as  the  water  is  saturated, 

*  All  gases  that  are  heavier  than  the  atmosphere,  may  be  collected 
in  this  way,  and  those  that  are  lighter  may  be  collected  by  inverting 
the  bottle,  and  pressing  the  air  down,  instead  of  lifting  it  up. 


Physical  and  Comical  Properties.  155 

Fig.  73. 


the  gas  passes  through  the  tube  to  the  bottom  of  d,  and  as- 
cends again  through  the  water;  thence  to  r,  in  a.  similar 
manner.  Through  the  centre  of  each  bottle  there  is  a  safety 
tube,  extending  nearly  to  the  bottom,  to  prevent  the  danger 
tli  it  might  arise  from  a  too  sudden  evolution  of  gas.  The 
gas  presses  upon  the  surface  of  the  water,  and  forces  it  up 
the  centre  tubes,  which  prevents  it  from  bursting  the  bottles. 
The  acid  in  the  first  bottle  is  thrown  away ;  the  rest  is  the 
acid  of  commerce.  The  bottles  should  be  surrounded  with 
ice,  to  aid  the  absorption  :  water  will  thus  absorb  480  times 
its  volume,  and  the  solution  has  a  density  of  1.2109. 

Physical  Properties.  Hydrochloric  acid  gas  is  colorless, 
of  a  pungent  odor,  and  acid  taste,  a  little  heavier  than  the 
air;  sp.  gr.  1.269  ;  under  a  pressure  of  forty  atmospheres,  or 
600  Ibs.  on  the  square  inch,  it  is  condensed  into  a  liquid. 

Chnnical  Properties.  It  possesses  decidedly  acid  proper- 
ties, changes  ihe  vegetable  infusions  red,  and  combines  with 
alkalies,  and  forms  salts.  It  supports  combustion  feebly,  and 
extinguishes  a  lighted  taper,  the  flame  of  which  assumes  a 
greenish  hue  before  it  goes  out.  Water  absorbs  it  rapidly. 

Exp.  A  drop  or  two  of  cold  water,  introduced  into  a  flask  of  the 
acid,  will  absorb  it  readily  ;  and  if  a  jar  of  it  be  inverted  over  water, 
the  water  will  rush  in  with  nearly  the  same  violence  as  into  a  vacuum. 

Exp.  So  strong  is  its  affinity  for  water,  that  a  piece  of  ice  introduced 
into  a  jar  of  it  over  mercury,  will  be  dissolved  almost  as  soon  as  if 
thrown  into  a  furnace. 

It  is  readily  decomposed  by  voltaic  electricity,  the  hydrogen 
appearing  at  the  negative  and  the  chlorine  at  the  positive 
pole.  A  discharge  of  ordinary  electricity  will  decompose  it, 
but,  according  to  Henry,  the  second  shock  causes  it  to  com- 
bine again.  It  is  decomposed  by  those  substances  which 


156  Hydrochloric  Acid. 

yield  oxygen  readily,  such  as  the  peroxide  of  manganese, 
cobalt,  and  lead ;  the  oxygen  combines  with  the  hydrogen  of 
the  acid,  and  sets  the  chlorine  at  liberty. 

It  is  nearly  as  suffocating,  when  taken  into  the  lungs,  as 
chlorine,  causes  spasms  of  the  glottis,  and  combines  with  the 
saliva,  or  water,  and  forms  the  liquid  acid. 

Constitution.  It  was  formerly  supposed  to  be  a  simple 
body,  combining  with  oxygen  to  form  oxymuriatic  acid,  now 
found  to  be  chlorine.  But  its  composition  may  be  determined 
synthetically,  by  mixing  equal  portions  of  hydrogen  and  chlo- 
rine in  a  glass  tube,  and  exposing  them  to  the  solar  rays, 
when  they  instantly  combine,  with  explosion,  and  hydrochlo- 
ric acid  is  the  only  product ;  or  their  union  may  be  effected 
by  passing  an  electric  spark  through  the  mixture  contained 
in  the  eudiometer.*  If  the  gases  are  mixed,  they  will  com- 
bine slowly  in  diffuse  daylight.  The  light  from  the  point,  of 
charcoal,  at  the  poles  of  a  galvanic  battery,  has  the  same 
effect  as  the  sun's  rays. 

Uses.  Hydrochloric  acid  is  one  of 'the  three  great  acids 
used  in  the  arts ;  it  is  used  for  preparing  the  chloride  of  tin 
for  dyers,  as  a  re-agent  in  various  chemical  processes,  and 
in  medicine  as  a  tonic. 

fm]>urities. ~  The  acid  of  commerce  is  not  quite  pure,  containing 
the  chloride  of  iron,  and  chlorine.  This  -MVCS  the  liquid  a  yellow 
color;  but,  \vhen  perfectly  pure,  it  is  limpid. 

Hydriodic  Acid.  Symb.  II  + 1.  Eq.  12G.3  +  1  =  127  .:*. 
Sp.  gr.  4.3854,  air=:l.  Discovered  by  Gay  Lussac,  of  Paris. 

Preparation.  It  may  be  obtained  by  passing  iodine  vapor 
and  hydrogen  gas  through  a  red-hot  porcelain  tube.  But  a 
more  convenient  process,  by  which  it  may  be  obtained  lor 
the  purposes  of  experiment,  is  to  put  a  small  bit  of  phosphorus 
into  a  glass  tube,  filled  with  water,  and  drop  upon  it  a  few 
grains  of  iodine. 

Theory.  The  iodine  unites  with  the  phosphorus,  forming 
the  periodide  of  phosphorus,  and  then  the  water  and  the 
periodide  mutually  decompose  each  other.  The  oxygen  of 

*  The  fact  being  established  that  hydrochloric  acid  is  composed 
of  hydrogen  and  chlorine,  the  old  theory  that  oxygen  was  the  only 
acidifying  principle  is  proved  false;  there  are  many  acids  of  hydrogen 
which  have  no  oxygen  in  them.  They  are  called  hydracids. 


Hydrofluoric  Acid.  157 

the  water  unites  with  the  phosphorus,  and  the  hydrogen  with 
the  iodine,  giving  rise  to  phosphoric  and  hydriodic  acids ;  the 
latter  passes  over  in  the  form  of  a  colorless  gas,  and  may  be 
collected  in  a  receiver  of  common  air ;  it  may  be  passed 
through  water,  and  absorbed  by  it.  It  cannot  be  collected 
over  mercury,  because  it  acts  upon  it. 

Properties.  Hydriodic  acid  is  a  colorless,  transparent  gas, 
very  sour  to  the  taste,  anil  gives  an  odor  like  hydrochloric 
acid ;  reddens  vegetable  blues  without  destroying  them,  and, 
when  mixed  with  air,  produces  dense  white  fumes ;  has  a 
strong  affinity  for  water ;  is  decomposed  by  several  of  the 
metals,  such  as  potassium,  sodium,  zinc,  iron,  and  mercury, 
and  even  when  exposed  to  the  air. 

Uses.     This  acid  may  be  employed  to  form  pigments. 

EJ }>.  Take  some  of  the  salts  of  lead  (acetate  or  nitrate  of  lead)  in 
solution,  and  pour  on  hydriodic  acid;  it  will  decompose  the  salt,  and 
form  paints  of  a  yellow  color. 

Tests.  The  most  delicate  test  of  this  acid  is  bichloride  of 
platinum,  a  single  drop  of  which,  in  solution,  will  give  to  a 
liquid  containing  the  acid,  a  reddish-brown  color,  and  a  dark 
precipitate  will  subside. 

Exp.  Starch  is  also  a  sure  test.  A  few  drops  of  sulphuric  acid  will 
give  to  a  solution  of  the  acid,  mixed  with  a  cold  solution  of  starch,  a 
blue  color. 

Hydrobromic  Acitl.  Symb.  Br  +  H  or  BrH.  Eq.78.4  +  J 
—  79.4.  Sp.  gr.  2.735-3.  Discovered  by  M.  Balard,  and  may 
be  obtained  by  immersing  a  red-hot  iron  into  a  mixture  of 
the  vapor  of  bromine  and  hydrogen ;  the  combination  takes 
place  slowly,  without  explosion ;  or  it  may  be  formed,  for  ex- 
perimental purposes,  by  a  process  similar  to  that  for  obtaining 
hydriodic  acid,  using  bromine  instead  of  iodine. 

Properties.  It  is  colorless,  with  an  acid  taste  and  pungent  odor ; 
irritates  the  glottis,  so  as  to  excite  couching  ;  exposed  to  moist  air,  it 
yields  white  dense  vapors,  and  is  rapidly  absorbed  by  water  ;  decom- 
posed by  chlorine  instantly ;  nitric  acid  also  effects  its  decomposition. 

Hydrofluoric  Acid.  Symb.  F  +  H  or  FH.  Eq.  18.68  -(-  1 
=  19.68.  Sp.  gr  1.0609. 

History.  First  procured  in  a  pure  state  in  1810,  by  Gay 
Lussac  and  Thenard. 

Process.  It  is  formed  by  the  action  of  sulphuric  acid  on 
fluor-spar,  (  fluoride  of  calcium.)  This  mineral  is  pulverized, 
14 


158  Nitrogen. 


put  into  a  lead  or  silver  retort,  with  twice  its  weight  of  sul- 
phuric acid,  and  heat  applied.  The  acid  will  distil  over,  and 
must  be  collected  in  a  vessel  of  the  same  material,  surrounded 
with  ice,  to  condense  the  acid. 

Theory.  The  hydrogen  of  the  water  in  the  sulphuric  acid  combines 
with  the  fluorine  in  the  mineral,  and  the  oxygen  with  the  calcium  ; 
the  sulphuric  acid  unites  with  the  oxide  of  calcium  :  the  products  are 
hydrofluoric  acid,  and  sulphate  of  the  protoxide  of  calcium.  Ca,  F,  SO3 
and  HO  are  converted  into  CaO  +  SO3  and  FH. 

Properties.  At  32°  F.  it  is  a  colorless  liquid,  and  remains 
in  that  state  at  593,  if  preserved  in  well-stopped  bottles;  but, 
exposed  to  the  air,  it  assumes  the  gaseous  form,  unites  \\  itli 
the  water  of  the  atmosphere,  producing  white  fumes.  Its 
affinity  for  water  is  greater  than  strong  sulphuric  acid.  Its 
vapor  is  much  more  pungent  than  chlorine  or  any  of  the  irri- 
tating gases;  the  most  aeffnto&NW  to  animal  matter  of  any 
known  substance,  a  single  drop  of  the  concentrated  acid 
causing  deep  and  almost  incurable  ulcers.  It  is  distinguished 
for  the  remarkable  property  of  acting  on  glass.  It  readily  dis- 
solves silex,  and  an  acid  is  produced  called  the  Jtuo-silicir. 
acid;  and  hence  it  cannot  be  preserved  in  glass  vessels. 

Uses.     It  is  used  for  etching  on  glass. 

Exp.  For  this  purpose,  prepare  some  resin  or  beeswax,  and  form 
a  coat  over  the  glass  ;  then,  with  a  pointed  instrument,  remove  the 
coating  where  you  wish  the  glass  to  be  etched ;  ponr  on  the  acid, 
and  in  a  few  minutes  the  etching  is  completed.  Then,  by  wash- 
ing the  glass  in  water,  and  removing  the  coating,  the  figures  will 
appear.  The  liquor  in  the  retort  will  answer  for  this  experiment,  es- 
pecially if  used  within  a  day  or  two  after  the  acid  and  the  fluor-spar 
are  mixed. 


SECT.  7.     NITROGEN. 
Sym,,N.      E,ulT.{*  ;£'«»,,.      Bp.P.  {*™  ft,  =  j; 

History.  Nitrogen  was  discovered  by  Dr.  Rutherford,  of 
Edinburgh,  in  1772.  Three  years  after,  Lavoisier  discovered 
that  it  was  a  constituent  of  the  atmosphere.  Scheele  also 
made  the  same  discovery.  It  was  called  by  Lavoisier  azote, 
(from  two  Greek  words,*)  because  it  deprived  animals  of  life  ; 
but  this  is  not  the  only  gas  which  is  azotic.  Its  present 
name,  nitrogen,  is  derived  from  nitre,  (nitrate  of  potassa.) 

*  A  and  £<,»• 


Physical  and  Chemical  Properties.  159 

Natural  History.  Nitrogen  exists  in  all  animals,  in  fun- 
gous plants,  and  constitutes  £  of  the  atmosphere;  also  in 
some  hot  springs  in  Scotland,  and  in  the  Alps.  It  is  also 
evolved  from  certain  springs  in  the  state  of  New  York. 

Process.  It  may  be  obtained  from  the  atmosphere,  either 
by  burning  out  the  oxygen  of  a  confined  portion  of  air  with 
some  combustible,  or  by  abstracting  the  oxygen  in  a  more 
gradual  way,  by  its  affinity  for  some  of  the  simple  substances. 

Exp.  1.  Put  a  small  piece  of  phosphorus  in  a  cup 
which  will  float  on  water,  (Fig.  74,)  and  invert  over  Fig.  74. 
it  a  receiver  of  common  air.  On  igniting  the  phos- 
phorus, it  will  unite  with  the  oxygen,  ana  burn  until 
all  the  oxygen  is  consumed,  forming  white  fumes  — 
the  pyrophosphoric  acid.  This  acid,  in  a  short  time, 
will  be  absorbed  by  the  water,  which  will  rise  and  fill 
the  jar  J-  full.  This  is  sufficiently  pure  for  common 
experiments,  but  contains  vapor  of  phosphorus  and 
carbonic  acid,  which  may  be  removed  by  passing  the 
gas  through  pure  potassa. 

Exp.  2.  Make  a  paste  of  flowers  of  sulphur  and  iron  filings,  and  invert 
over  it  a  receiver;  the  oxygen  will  combine  slowjy  with  the  iron,  and 
leave  the  nitrogen.  A  stick  of  phosphorus  will  produce  the  same  ef- 
fect. If  the  proto-sulphate  of  iron,  charged  with  the  binoxide  of  nitro- 
gen, be  substituted  for  the  paste,  the  process  is  more  rapid. 

Exp.  3.  It  may  also  be  obtained  by  pouring  nitric  acid  on  fresh 
muscle,  and  subjecting  it  to  a  moderate  heat. 

Theory.  On  account  of  the  strong  affinity  of  oxygen  for 
these  substances,  it  leaves  the  nitrogen,  and  combines  with 
them. 

Physical  Properties.  Nitrogen  is  colorless,  tasteless, 
inodorous,  not  condensed  into  a  solid  by  pressure  or  cold. 
100  cubic  inches  weigh  30.1650  grains. 

Chemical  Properties.  Water,  recently  boiled,  absorbs  1 J 
volumes  of  the  gas. 

Nitrogen  will  not  support  combustion. 

Exp.  Put  a  lighted  candle  into  a  jar  of  it,  and  it  will  be  immediately 
extinguished  ;  hence  it  does  not  snp/tort 

Respiration.  No  animal  can  live  in  it,  not  because  of  the 
active  properties  of  the  gas,  but  because  it  excludes  the  oxy- 
gen. .  It  kills  by  its  negative  properties,  for  which  it  seems 
alone  to  be  distinguished.  The  effect  is  like  that  of 
drowning. 

Nature  of  Nitrogen.      Nitrogen  has   been  supposed   by 


160  Nitrogen  and  Oxygen. 

some,  among  whom  is  Berzelius,  to  be  a  body  compose  J  o" 
oxygen  and  an  unknown  base.  But  this  base  has  never  been 
exhibited  in  a  separate  state ;  and,  until  that  is  done,  it  must 
be  regarded  as  a  simple  substance. 

Although  pure  nitrogen  is  the  most  inert  of  substances, 
some  of  its  compounds  are  among  the  most  active  and  useful. 

Nitrogen  and  Oxygen. 

Common  Air.  Symb.  2N  +  O.  Equiv.  28.30  +  8  = 
36.30,  eq.  vol.  4N+O.  Sp.  gr.  =  1.  Th6  earth  is  sur- 
rounded by  a  gaseous  fluid  or  atmosphere,  consisting  chiefly 
of  common  air,  extending  about  forty-five  miles  from  its  sur- 
face, and  revolving  with  it  around  the  sun. 

Physical  Properties.  The  atmosphere  is  a  permanent, 
elastic  fluid,  transparent,  inodorous,  and  tasteless. 

The  air  is  very  compressible. and  elastic 

EXD.  The  compressibility  of  the  air  may  be  shown  by  the  fire-syringe, 
by  which  it  may  be  compressed  into  a  very  small  compass.  If  100 
measures  of  confined  air,  under  pressure  of  1  lb.,  be  subjected  to  double 
the  pressure,  or  2  Ibs.,  it  will  be  diminished  to  50  measures;  double 
this  pressure,  or  4  Ibs.,  will  compress  it  to  25  measures.  On  the  other 
hand,  if  the  pressure  be  diminished,  its  elasticity  will  restore  it  to  iU 
former  state.  Then,  if  £  lb.  be  applied  to  the  100  measures,  it  will  ex- 
pand to  200  measures.  Halve  this,  or  4  of  a  pound,  and  the  volume 
will  be  double,  or  400  measures.  The  same  is  true  of  all  other  gaseous 
bodies,  while  they  retain  their  gaseous  state.  Hence  the  following 
law,  that 

The  volume  of  air  and  of  other  gaseous  fluids  is  inversely 
as  the  pressure  applied. 

Exp.  The  rlafticitif  of  the  air  may  be  further  shown  by  putting  a 
bladder,  half  filled  with  air,  under  the  receiver  of  an  air-pump,  and 
exhausting  the  air  from  the  receiver;  the  external  pressure  being  thus 
taken  off,  the  air  within  the  bladder  will  expand,  fill  the  bladder,  and 
even  burst  it.  This  force  is  often  so  great,  as  to  burst  the  strongest 
vessels.  Hence  the  danger  of  forcing  too  much  air  into  the  ball  oFan 
air-gun,  or  carbonic  acid  into  a  soda  fountain. 

Winds.  In  consequence  of  the  great  elasticity  and  compressibility 
of  the  air,  it  gives  rise  to  the  phenomena  of  winds.  It  is  subject  to  the 
laws  of  elastic  fluids  in  general ;  as  one  portion  therefore  becomes  ex- 
panded by  heat,  the  colder  or  more  dense  portions  rush  rapidly  into 
its  place,  and  force  it  to  ascend.  From  the  same  properties,  also,  vi- 
brations are  easily  produced  in  it,  which  give  rise  to  the  sensation  of 
sound,  musical  tones,  etc. 

Pressure  of  the  Air.  That  the  air  had  weight,  was  first 
noticed  by  Galileo,  in  1640.  Torricelli,  his  pupil,  carried  out 


Common  Air.  161 

his  suggestions,  and  in  1643  invented  the  barometer*  by 
which  variations  of  pressure  could  be  accurately  measured. 
The  exact  weight  of  the  atmosphere  is  of  great  importance 
in  physical-and  chemical  researches,  and  has  been  accurately 
determined  by  Dr.  Prout.  At  the  level  of  the  sea,  its  pressure 
is  15  Ibs.  on  every  square  inch  of  surface. 

Exp.  This  pressure  may  be  illustrated  by  exhausting  the  air  from 
the  receiver  of  an  air-pump ;  the  pressure  on  the  external  surface  of 
the  receiver  will  fix  it  immovably  to  the  plate. 

The  body  of  a  man  sustains  constantly  a  pressure  of  about 
14  tons ! 

As  we  ascend  above  the  level  of  the  sea,  the  mercury  sinks 
in  the  barometer,  because  the  column  of  air  is  shorter ;  hence 
the  height  of  mountains  may  be  measured  in  a  very  expeditious 
manner.  Aeronauts  in  this  manner  determine  the  height  to 
which  they  ascend. t 

Extent  of  the  Atmosphere.  The  height  of  the  atmosphere, 
as  estimated  by  the  phenomena  of  refraction,  is  found  to  be 
about  forty-five  miles.  Above  that  height,  no  refraction  takes 
place  hi  the  rays  of  light.  Dr.  Wollaston  estimates  its  ex- 
tent, by  the  law  of  the  expansion  of  gases,  at  forty  miles  ; 
that  is,  the  weight  of  the  particles  of  air  (gravity)  will  over- 
come their  elasticity  at  that  height. 

Composition  of  the  Atmosphere.  Chemists  are  not  agreed 
whether  the  atmosphere  is  a  chemical  or  a  mechanical  com- 
pound. The  proportions  20  or  21  parts  of  oxygen  and  79  or 
80  of  nitrogen  in  100  never  vary,  from  whatever  parts  of  the 
earth,  or  regions  of  the  atmosphere,  it  may  be  taken.  Gay 
Lussac  brought  air  from  an  altitude  of  21,735  feet,  and  its 
composition  did  not  vary  from  that  on  the  surface  of  the  earth. 

Exp.  That  the  atmosphere  is  composed  of  4  parts  of  nitrogen  arid 
1  of  oxygen,  by  measure,  may  be  shown  by  a  graduated  glass  tube  of 

*  Torricelli  first  filled  a  glass  tube  three  feet  in  length  with  mercury, 
and,  on  inverting  it  in  a  vessel  of  the  same  liquid,  found  that  the  mer- 
cury fell  about  six  inches ;  hence  the  atmosphere  sustained  a  column 
of  mercury  of  about  thirty  inches.  The  space  abandc.ied  by  the 
mercury  is  called  the  Torricellian  vacuum,  and  is  the  most  perfect 
that  can  be  formed. 

t  There  seems  to  be  a  constant  relation  between  the  pressure  of  the 
atmosphere  and  the  weather.  During  a  storm,  the  mercury  in  the 
barometer  sinks,  indicating  that  the  atmosphere  is  lighter,  and  rises 
again  when  fair  weather  returns,  proving  its  greater  weight.  Invalids 
often  complain  of  the  oppressive  weight  of  air  in  foul  weather ;  the 
fact,  as  we  have  seen,  is  the  reverse ;  they  feel  a  difficulty  in  respira- 
tion, because  the  air  is  too  light.  The  same  difficulty  is  felt  by  aero- 
nauts, and  those  who  ascend  high  mountains. 

14* 


162 


Nitrogen  and  Oxygen. 


known  capacity,  and  bent  as  in  Fig.  75.  Putabitof  Fig.  75. 
phosphorus  into  the  bent  end,  and  place  the  open 
end  in  a  vessel  of  water,  keeping  the  finger  over  the 
end  to  prevent  the  air  from  escaping.  Bring  now 
near  the  phosphorus  a  red-hot  iron ;  the  phospho- 
rus will  be  inflamed,  and  will  burn  out  the  oxygen 
of  the  air ;  phosphoric  acid  will  be  formed,  and 
absorbed  by  the  water;  the  latter  will  rise,  and  fill 
the  tube  l-5th  full;  the  remaining  4-5ths  is  nitro- 
gen. 

This  uniformity  in  the  composition  of  the 
atmosphere  has  been  regarded  as  a  decisive 
proof  of  its  chemical  constitution.  But  it  has 
been  shown  by  Dalton,  that  it  is  the  results  of 
a  mechanical,  rather  than  of  a  chemical  law. 
This  law  may  be  illustrated  in  the  following  manner :  — 

Exp.  Take  two  strong  glass  tubes  closed  at  one  end,  and  fill  the 
one  with  oxygen  and  the  other  with,  hydrogen  gas.  Close  the  tube  con- 
taining oxygen  with  a  cork,  through  the 'centre  of  which  is  inserted  a 
small  glass  tube.  Having  inverted  the  tube  containing  the  oxyifn, 
place  upon  it  that  containing  the  hydrogen,  so  that  one  cork  shall  rl<>s<> 
both  tubes;  let  thorn  remain  in  an  upright  position.  As  the  o.\y«rt  n  in 
the  lower  vessel  is  sixteen  times  as  heavy  as  the  hydrogen  in  the  upper, 
we  should  expect  that  eacli  would  maintain  its  position;  but  the  fact 
is  otherwise.  They  mutually  intermingle,  as  is  proved  by  their  forming 
explosive  mixtures  in  both  tubes. 

Similar  experiments  have  been  made  upon  a  great  number 
of  gases,  and  it  is  uniformly  found  that,  after  a  little  time,  they 
will  distribute  themselves  equally  through  the  space  occupied 
by  both,  whatever  be  their  difference  of  density  ;  hence  it  u  ,is 
inferred  by  Dalton  that  different  gases  are  vacuums  in  rrspcrt 
to  each  other;  that  is,  that  one  gas  does  not  prevent  the  en- 
trance of  another  into  the  space  which  it  occupies,  any  more 
than  the  vacuum  of  an  air-pump,  although  it  will  flow 
more  slowly  in  the  former  than  in  the  latter  case.  All  gases 
and  vapors  follow  the  same  law ;  hence  there  are  as  many  at- 
mospheres around  the  earth  as  there  are  gases  upon  its 
surface,  each  occupying  the  same  space  which  it  would  oc- 
cupy if  it  were  entirely  alone. 

This  tendency  to  diffusion  renders  it  difficult  to  confine 
gases  in  bladders,  or  even  over  water  in  the  pneumatic  cistern. 

Exp.  By  placing  hydrogen  gas  in  a  glass  tube,  one  end  of  which  is 
stopped  by  plaster  of  Paris,  over  water,  the  hydrogen  will  force  itself 
out  through  this  plaster  so  rapidly  as  to  prevent  the  entrance  of  the 
air,  and  the  water  will  rise  in  the  tube ;  but,  as  the  water  rises,  the  at- 
mospheric pressure  is  such  as  to  force  the  air  into  the  tube,  and  the 
water  will  fall.  By  igniting  the  gas,  it  will  explode  ;  which  shows  that 
there  has  been  a  mingling  of  the  air  with  the  hydrogen. 


Protoxide  of  Nitrogen.  163 

Impurities.  The  air  usually  contains  other  gases;  car- 
bonic acid  and  watery  vapor  are  the  most  abundant.  The 
quantity  of  water  is  determined  by  the  hygrometer.  It  never 
amounts  to  more  than  one  per  cent.  Carbonic  acid  rarely 
exceeds  iifov  Traces  of  hydrochloric  acid  are  frequently 
found  in  the  vicinity  of  the  ocean,  and  of  nitric  acid  in  rain 
water,  produced  by  lightning. 

The  air  ne'ir  cities  often  contains  other  substanfres,  organic 
matter,  sulphuric  acid,  and  ammonia.  The  odoriferous  par- 
ticles of  flowers,  and  other  vegetable  and  mineral  substances, 
are  often  detected  in  it. 

It  was  formerly  supposed,  that  the  healthy  state  of  the  air 
depended  upon  the  proportion  of  oxygen  in  it ;  hence  the 
origin  of  the  term  ctfr/in/mtry,  which  was  applied  to  the 
process  of  analyzing  the  air;  but,  since  the  oxygen  of  the 
air  is  found  to  be  constant,  it  is  now  applied  also  to  the 
modes  of  ascertaining  its  purity.  This  is  effected  either 
by  exploding  a  given  portion  of  air  with  hydrogen  in  the 
(H'l'onutcr,  (see  page  152,)  or  by  placing  in  a  portion  of 
confined  air  some  substance  to  abstract  the  oxygen. 

Uses  of  the  Air.  The  utility  of  the  atmosphere  in  the  economy  of 
nature  cannot  be  too  highly  rated.  It  is  absolutely  essential  to  animal 
and  vegetable  life.  Its  constitution  is  one  of  the  most  beautiful  illus- 
trations of  the  wisdom  and  goodness  of  the  Creator. 

Protoxide  of  Nitrogen.  Symb.  NO.  Equiv.  14.15  +  8  = 
22.15.  Sp.  gr.  1.5239.  100  cubic  inches  weigh  47.2536  grains. 

History.  Discovered  by  Priestley,  1772,  and  named  by 
him  dephlogisticated  nitrous  air.  Davy  called  it  nitrous  oxide. 

Process.  This  gas  may  be  formed  by  decomposing  nitrate 
of  ammonia. 

Exp.  Put  a  few  grains  of  this  salt  into  a  glass  retort,  and  apply 
heat.  At  a  temperature  of  between  400°  and  500°  Fahr.  it  liquefies, 
bubbles  of  gas  begin  to  appear,  and  in  a  short  time  brisk  effervescence. 
The  gas  may  then  be  collected  in  the  ordinary  way  over  warm  water, 
and  suffered  to  remain  a  short  time,  until  the  water  absorbs  the  nitrous 
acid  which  is  often  formed  with  it. 

Tlicory.  The  changes  which  take  place  may  be  thus  ex- 
plained :  the  NH3-f-NO5,  containing  2N,  5O,  and  3H,  are 
converted  into  3HO,  or  water,  and  2NO. 

Properties.  The  protoxide  of  nitrogen  is  a  colorless,  in- 
odorous gas,  of  a  sweetish  taste,  and  does  not  affect  the  vege- 
table blues ;  it  is  rcot,  therefore,  an  acid  or  an  alkali. 


164  Nitrogen   and  Oxygen. 

It  supports  combustion  almost  as  powerfully  as  oxygen  gas. 

Ezp.  A  candle  is  relighted  in  the  same  manner  as  in  oxygen  gas. 
Iron  wire,  charcoal,  and  most  combustibles,  burn  in  it.  Phosphorus 
burns  with  nearly  the  same  brilliancy  as  in  oxygen  gas. 

Exp.  Mix  equal  volumes  of  the  protoxide  and  hydrogen  gas,  and  it  will 
form  an  explosive  mixture,  which  may  be  exploded  in  the  gas  pistol 
by  flame,  or  the  electric  spark ;  but  generally  it  requires  the  temperature 
of  the  substance  to  be  raised  to  a  higher  degree  than  oxygen,  because 
the  heat  is  necessary  to  decompose  the  gas,  so  that  its  oxygen  may 
unite  with  the  combustible,  and  its  nitrogen  escape  into  the  air. 

Respiration  of  this  Gas.  When  respired,  it  is  a  powerful 
stimulant.  Its  effects  upon  the  animal  system  were  first  in- 
vestigated by  Sir  H.  Davy  in  1799.  In  his  experiments  on 
the  effects  of  respiring  the  various  gases,  he  breathed  nine 
quarts  of  this  gas  for  three  minutes,  and  twelve  quarts  for 
four.  No  quantity  would  *tt/>jnn't  n  ffjirntinn  for  a  longer 
period.  The  effects  are  pleasurable  in  the  highest  degree, 
resembling  the  first  stages  of  intoxication.  The  effect  varies 
very  much  with  temperament,  but  generally  gives  an  unusual 
propensity  to  muscular  action,  a  rapid  flow  of  vivid  ideas, 
and  the  more  prominent  traits  of  character  are  made  ttill 
more  prominent. 

This  excitement  continues  but  for  a  few  minutes,  and  gen- 
erally is  not  succeeded  by  the  languor  and  exhaustion  conse- 
quent upon  other  stimulants.*  Its  effects,  however,  upon  some 
temperaments,  have  proved  decidedly  injurious.  It  is  hoped 
that  so  powerful  a  stimulant  will  be  applied  to  some  good  use 
in  medicine. 

Binoxide  of  Nitrogen.  Symb.  N  +  2O,  NO2  or  N.  Eq. 
14.154-16  =  30.15.  Sp.  gr.  1.0375. 

History.  Discovered  by  Dr.  Hales ;  but  its  properties  were 
first  investigated  by  Dr.  Priestley,  in  1772,  who  gave  it  the 
name  of  nitrous  air.  Nitric  oxide  and  nitrous  gas  have  also 
been  applied  to  it. 

Process.  It  may  be  formed  by  the  action  of  dilute  nitric 
acid  (2  parts  of  water  to  1  of  acid)  upon  copper  filings,  or 


*  It  may  be  administered  from  a  silk  or  India-rubber  bag,  furnished 
with  a  stop-cock,  by  repeatedly  breathing  it  from  the  bag  and  back 
again,  as  long  as  it  will  support  easy  respiration. 


Nitrous  Acid.  165 

mercury.     Place  the  materials  in  a  retort,  and  collect  over 
water.  • 

Theory.  In  this  process,  the  nitric  acid  is  decomposed.  3  equiv.  of 
oxygen  unite  with  the  copper,  forming  the  peroxide  of  copper,  and  2 
equiv.  of  oxygen  combine  with  the  nitrogen,  and  form  the  binoxide ;  the 
peroxide  of  copper  is  then  united  to  some  undecomposed  nitric  acid, 
and  forms  the  nitrate  of  copper.  Cu  and  !^NO5  are  converted  into 
Cu03-fNO5and  NO2. 

Properties.  This  gas  is  colorless,  and  slightly  absorbed 
by  water.  It  is  perfectly  irrespirable,  exciting  spasms  in  the 
glottis,  which  immediately  closes  to  prevent  its  passage  into 
the  lungs.  It  extinguishes  most  burning  bodies,  although 
phosphorus  and  charcoal,  introduced  in  a  state  of  vivid  com- 
bustion, burn  with  increased  brilliancy,  owing,  doubtless,  to 
its  decomposition,  which  is  easily  effected  by  heat  or  elec- 
tricity. 

Binoxide  of  nitrogen  has  a  strong  affinity  for  oxygen. 

Exp.  Pass  oxygen  into  a  jar  of  it,  and  red  fumes  will  be  formed. 
This  is  a  test  of  the  gas.  Atmospheric  air  will  produce  a  similar  ef- 
fect ;  *  hence  it  may  be  used  to  separate  the  oxygen  from  the  nitrogen 
of  the  air. 

Hyponitrous  Acid.  Symb.  N  +  3O,  NO3  or  N.  Equiv. 
14.15-^24  =  38.15.  This  compound  was  discovered  by 
Gay  Lussac,  and  is  said  to  be  formed  when  400  measures  of 
binoxide  of  nitrogen  are  mixed  with  100  of  oxygen,  both 
quite  dry.  When  the  resulting  orange  fumes  are  exposed  to 
a  cold  of  zero,  Fahr.,  they  are  condensed  into  a  liquid. 

Properties.  The  anhydrous  acid  is  colorless  at  zero,  and 
green  at  common  temperatures.  It  is  so  volatile,  that,  in  open 
vessels,  the  green  fluid  wholly  and  rapidly  passes  off  in  the 
form  of  an  orange-colored  vapor,  density  of  1.72.  In  the 
manufacture  of  sulphuric  acid,  it  exerts  an  important  agency, 
by  forming  with  water  and  sulphuric  acid  a  crystalline  com- 
pound, the  production  of  which  seems  essential  to  the 
process. 

Nitrous  Acid.  Symb.  N  +  4O,  NO4  or  N.  Eq.  14. 15  -f 
32  —  46.15. 

History.  Known  for  some  time  under  the  name  of  fuming 
nitrous  acid.  Its  true  nature  has  been  ascertained  by  Davy, 
Gay  Lussac,  and  Dulong. 

*  Owing  to  this  property,  an  attempt  has  been  made  to  introduce  it 
into  cudiometry  ;  but  the  results  are  not  perfectly  satisfactory. 


166  Nitrogen  and  Oxygen. 

Processes.  1.  It  is  formed  by  adding  oxygen  gas  in  excess 
to  the  binoxide  of  nitrogen  over  mercury,  and  putting  a  strong 
solution  of  potassa  into  the  receiver  before  mixing  the  gases  ; 
red  fumes  appear,  and  combine  with  the  potassa. 

2.  It  may  be  obtained  in  the  form  of  a  gas,  by  exhausting 
a  glass  globe  of  air,  and  introducing  100  volumes  of  oxygen 
to  200  volumes  of  the  binoxide  of  nitrogen.* 

3.  The  best  mode  is  to  expose,  in  an  earthen  retort,  nitrate 
of  lead,  carefully  dried,  to  a  red  heat,  and  collect  the  gas  in 
a  tube  surrounded  by  ice.     For  the  purposes  of  experiment, 
it  may  be  formed  by  introducing  oxygen,  or  common  air,  into 
a  jar  of  the  binoxide,  over  water;  deep  orange-red  colored 
fumes  appear,  which  are  rapidly  absorbed  by  the   water  ;  or 
by  simply  taking  up  a  jar  of  the  binoxide,  and  exposing  it  to 
the  air.     In  each  case,  nitrous  acid  is  formed,  and  may  be 
known  by  its  red  fumes. 

Properties.  The  vapor  is  of  an  orange-red  color,  rapidly 
absorbed  by  water.  At  common  temperatures,  the  liquid  is 
orange-red  ;  below  32°,  yellow,  and  nearly  colorless  at  zero, 
Fah?.  ;  density,  1.451  ;  anhydrous,  exceedingly  volatile,  pun- 
gent to  the  taste,  and  powerfully  corrosive,  giving  a  yellow 
stain  to  the  skin. 

It  has  decided  acid  properties,  t  both  in  the  gaseous  and 
liquid  states. 

Exp.  Into  a  long  glass  tube,  filled  partly  with  vegetable  infusion, 
and  partly  with  the  binoxide,  introduce  a  frw  bubbles  of  oxygen  ;  the 
infusion  will  immediately  turn  red,  owing  to  the  formation  ol  nitrous 
acid,  and  the  absorption  of  it  by  the  infusion. 

Respiration  of  Nitrous  Acid.  It  is  highly  suffocating  and 
poisonous,  exciting  great  irritation  and  spasms  in  the  glottis, 
even  when  moderately  diluted  with  air. 

Nitric  Acid.     Symb.  N  +  5O,  NO5  or  N.     Equiv.  14.15 
=  54.15. 


History.  This  acid  was  first  discovered  in  distilling  a 
mixture  of  nitrate  of  potassa  and  clay,  by  Raymond  Lully, 

*  If  collected  over  water,  it  is  converted  into  nitric  acid;  if  over 
mercury,  it  is  decomposed,  and  the  mercury  is  oxidized. 

t  Some  chemists  believe  it  to  be  a  compound  of  nitric  and  hyponi- 
trous  acids,  from  the  fact  that,  when  it  is  added  to  an  alkaline  solution, 
the  products  are  a  nitrate  and  a  hyponilrite  of  the  base. 


Nitric  Acid. 


167 


Fig.  76. 


a  chemist  of  the  Island  of  Majorca.  Basil  Valentine,  in  the 
15th  century,  describes  a  process  of  obtaining  it,  and  calls  it 
the  water  of  nitre.  Its  composition,  however,  was  first  de- 
termined by  Mr.  Cavendish,  in  1785,  by  exposing  oxygen  and 
nitrogen  in  a  glass  tube  over  mercury,  in  which  some  water 
was  present,  to  the  action  of  the  electric  battery.  It  has 
since  been  examined  by  Davy,  Dalton,  Henry,  Berzelius,  and 
Gay  Lussac. 

Process.  Gay  Lussac  ob- 
tained nitric  acid  by  adding  the 
binoxide  of  nitrogen  slowly  to 
an  excess  of  oxygen  over  water. 
By  this  process,  it  is  found  to 
be  composed  of  250  volumes  of 
oxygen  to  100  of  nitrogen.  But 
the  usual  process  for  obtaining 
it,  is  to  heat,  in  a  large  tubulated 
retort,  a,  (Fig.  76,)  a  mixture 
of  3  parts  of  nitre  (nitrate  of  po- 
tassa)  and  2  of  sulphuric  acid,* 
and  condensing  the  gas  in  the 
globe  receiver  6,  by  dropping 

ice-cold  water  from  the  tunnel  t  upon  the  tube  of  the  retort, 
or  by  surrounding  the  receiver  6  with  ice.  The  liquid,  as  it 
is  condensed,  passes  into  the  bottle  C. 

Impurities.  The  acid  of  commerce  is  not  perfectly  pure ;  three 
ncids  are  generated  in  the  process  —  the  nitrous,  hyponitrous,  and  nitric. 
It  also  contains  hydrochloric  and  sulphuric  acids  Nitrous.,  acid  gives 
it  a  color  varying  from  yellow  to  orange  and  green,  and  may  be  ex- 
pelled by  heat ;  the  hydrochloric  may  be  detected  and  separated  by  a 
few  drops  of  the  nitrate  of  silver,  with  which  it  will  combine  and  form 
a  white  solid.  The  sulphuric  acid  is  separated  by  re-distilling  it  with 
nitre. 

Properties.  Nitric  acid,  in  its  most  concentrated  state,  is 
a  \vhite, or  limpid  liquid,  specific  gravity  of  1.55,  and  of  a 
peculiarly  nauseous  odor.  It  boils  at  248°,  and  freezes  at 
-50°  Fahr. 


*  The  London  College  of  Physicians  employ  equal  weights  of  nitrate 
of  potassa  and  sulphuric  acid.  The  Edinburgh  and  Dublin  Colleges 
employ  3  of  nitre  to  2  of  acid.  According  to  Thompson,  the  strongest 
acid  is  obtained  from  6|  parts  of  sulphuric  acid  to  12|  of  nitre;  the 
specific  gravity  of  which  is  1.55. 


168  Nitric  Acid. 

Chemical  Properties.  It  is  one  of  the  most  energetic  of 
substances.  It  acts  upon  the  skin,  and  gives  it  a  yellow 
stain ;  it  is  eminently  poisonous ;  has  a  very  strong  affinity 
for  water,  and  cannot  be  wholly  separated  from  it,  before 
decomposition  takes  place. 

It  acts  as  a  supporter  of  combustion ;  in  this  case,  it  is 
decomposed,  and  the  oxygen  combines  with  the  combustible. 

Exp.   Pass  hydrogen  and   nitric  acid  through  an  ig-       Fijr.  77. 
nited  porcelain  tube ;  a  violent  detonation  will  be  pro- 
duced, which  is  due  to  the  combination  of  the  oxygon  of 
the  acid  and  the  hydrogen. 

Exp.  Pour  strong  nitric  acid  on  dry,  powdered  char- 
coal ;  the  charcoal  will  be  ignited,  with  the  evolution 
of  dense  fumes. 

Exp.  Phosphorus  takes  fire  in  it,  (Fig.  77,)  sometimes 
with  violent  explosion. 

Exp.  Pour  nitric  acid  on  to  some  of  the  essential  oils, 
as  spirits  of  turpentine,  and  they  will  be  iiiH;iin«-«l. 

The  acid  in  these  experiments  should  be  pour- 
ed from  a  wine-glass,  attached  to  the  end  of  a 
long  rod. 

Nitric  acid  unites  with  various  metals,  such  as  iron,  tin, 
copper,  with  great  energy,  and  is  decomposed  by  them.  It 
also  suffers  decomposition  by  boiling  it  in  contact  with 
sulphur,  or  by  exposing  it  to  the  solar  rays.  In  this  case, 
the  color  changes  to  a  yellow,  and  deep  orange,  in  conse- 
quence of  the  formation  of  nitrous  acid.  The  action  of 
the  binoxide  of  nitrogen  produces  the  same  effect,  as  may 
be  shown  by  passing  it  through  nitric  acid.  In  consequence 
of  its  yielding  up  its  oxygen  so  readily,  it  is  one  of  the  most 
powerful  oxidizing  agents. 

Uses.  It  is  used  extensively  in  chemistry  and  the  arts; 
for  etching  on  copper,  and  as  a  solvent  of  tin  to  form  a  mor- 
dant for  some  of  the  finest  dyes;  in  metallurgy  and  assaying, 
to  bring  the  metals  to  their  maximum  of  oxidation ;  in  medi- 
cine, as  a  tonic.  The  nitric  acid  of  commerce  is  J  water, 
and  called  double  aquafortis ;  another  kind,  j  water,  is  called 
simply  aquafortis. 

Nitrohydrocliloric  Acid.  This  is  the  aqua  regia  of  the 
alchemists,  and  is  formed  of  1  part  of  nitric  to  4  of  hydro- 


Nitrogen  and  Chlorine.  169 

chloric  acid.  It  possesses  the  remarkable  property  of  dissolv- 
ing gold  and  platinum,  but  does  not  form  a  distinct  class 
of  salts. 

NitroJiydrofluoric  Acid.  This  acid  is  formed  by  a  mixture 
of  nitric  and  hydrofluoric,  acids,  and  dissolves  metals,  which 
are  not  dissolved  by  the  preceding  acid,  and  is  therefore  an 
important  re-agent. 

Nitrogen  and  Chlorine. 

Quadrochhridc  of  Nitrogen.  Symb.  N  +  4C1  or  NCI4. 
Eq.  14.15  +  141.68  =  155.83.  Sp.  gr.  1.653.  Discovered 
hi  1811  by  Dulong,  and  subsequently  examined  by  Davy  and 
others. 

Process.  This  very  extraordinary  substance  may  be  formed  by  the 
union  of  nitrogen  and  chlorine  in  their  nascent  state,  or  the  chlorine 
may  be  obtained  in  ajar,  and  inverted  over  a  solution  of  J  part  of  hy- 
drochlorate  of  ammonia  to  12  of  water;  a  part  of  the  chlorine  unites 
with  the  hydrogen  of  the  ammonia,  forming  hydrochloric  acid,  and 
another  poition  unites  with  the  nitrogen  of  the  ammonia,  and  forms 
the  quadro-chloride  of  nitrogen,  which  appears  in  the  form  of  yellow, 
oily  drops  on  the  surface  of  the  solution. 

Properties.  A  yellow,  oily  liquid,  of  an  irritating  and  pe- 
culiar odor:  it  retains  the  liquid  state  below  zero,  Fahr.  It 
may  be  distilled  at  160°  Fahr.,  but  explodes  between  200°  and 
212°,  and  suffers  decomposition.  It  is- one  of  the  most  explo- 
sive substances  yet  known.  A  drop  of  the  size  of  a  pea, 
brought  in  contact  with  phosphorus,  or  with  any  of  the  oils, 
will  explode  with  great  violence.  It  is  dangerous  to  experi- 
ment with  it,  even  in  so  small  portions.  Dulong  lost  an  eye 
and  a  finger,  and  Davy  had  both  eyes  injured  by  exploding 
small  quantities  of  it.  As  it  is  liable  to  explode  without 
any  assignable  cause,  great  care  should  be  used  in  its  prepa- 
ration. 

Nitrogen  and  Iodine. 

Teriodide  of  Nitrogen.  Symb.  N  -f-  31  or  NP.  Eq.  14.15  + 
378.9  —  392.24.  This  compound,  discovered  by  M.  Cour- 
tois,  is  obtained  in  a  similar  manner  with  the  preceding. 

Exp.  Put  iodine  in  a  solution  of  ammonia,  and  there  will  be  precip- 
itated a  blackish  powder,  which  may  be  thrown,  in  the  course  of  half 
an  hour,  upon  a  filter,  washed  and  dried.  When  dry,  it  explodes  by 
the  slightest  touch,  or  even  spontaneously. 

15 


170  Nitrogen  and  Hydrogen. 


Nitrogen  and  Hydrogen. 

Ammonia.  Symb.  N-J-3H  or  NH8.  Eq.  14.15  +  3  = 
17.15. 

History.  This  substance  was  known  to  the  alchemists  by 
the  names  of  hartshorn,  volatile  alkali,  spirit  of  sal-ammo- 
niac, etc.,  but  was  first  noticed  as  a  distinct  gas  by  Dr.  Priest- 
ley, who  gave  it  the  name  of  alkaline  air.  The  name  ammo- 
nia is  derived  from  one  of  the  salts  from  which  it  was  pro- 
cured, the  hydrochlorate  of  ammonia,  or  sal-ammoniac,  and 
this  from  the  temple  of  Jupiter  Ammon,  in  Lybia,  from 
which  place  it  was  first  obtained. 

Process.     Mix  together  equal  parts  of  pulverized    Fig.  78. 
hydrochlorate  of  ammonia  and  recently-slacked  lime 
in  a  common  retort,  and  apply  heat.    The  gas  may 
be  collected  over  mercury,  or,  in  consequence  of  its 
being  lighter  than  the  air,  the  materials  may  be  put 
into  a  Florence  flask,  a,  (Fig.  78,)  to  which  is  at- 
tached a  long  glass  tube.     Invert  over  it  a  receiver, 
r,  and  the  gas  will  displace  the  air,  and  fill  the  re- 
ceiver; (for   a  test  of  the  gas,  hydrochloric  acid 
may  be  used,  which  produces  a  white  cloud.)     It 
may  also  be  obtained  by  simply  heating  the  com- 
mon aqua  ammonia  of  commerce.     The  liquid  ammonia,  or 
aqua  ammonia,  is  prepared  by  passing  the  gas  through  \\ 
in  Woulfe's  apparatus,  in  the  same  manner  as  in  the  prepa- 
ration of  hydrochloric  acid.     (Seepage  154.) 

Theory.  When  lime  and  the  hydrochlorate  of  ammonia  are  r.scd, 
the  hydrochloric  acid  deserts  the  ammonia,  and  combines  with  the  lime, 
leaving  the  former  to  escape  in  the  gaseous  form. 

Properties.  Ammonia  is  a  colorless  gas,  of  a  strong,  pun- 
gent odor ;  becomes  a  transparent  liquid  under  pressure  of 
6.5  atmospheres,  and  at  a  temperature  of  50°  Fahr.  It  cannot 
support  respiration  in  its  pure  state,  but  may  be  inhaled  with 
safety  when  mixed  with  the  air. 

It  is  inflammable,  but  extinguishes  the  flame  of  most  burn- 
ing bodies. 

Exp.  A  candle  immersed  in  this  gas,  burns  with  increased  flame, 
tinged  with  yellow  before  it  goes  out.  When  expelled  from  an  orifice 


Nitrogen  and  Hydrogen.  171 

surrounded  by  oxygen  gas,  and  ignited,  it  burns  with  a  pale  yellow 
flame.     The  products  are  water  and  nitrogen. 

It  has  a  strong  affinity  for  water  and  for  alcohol. 

Exp.   A  few  drops  of  water,  introduced   into  a  jar  of  the  gas  over 
mercury,  will  instantly  absorb  it,  and  the  mercury  will  rise. 
Ice  pliiced  in  ajar  of  it  over  mercury,  is  melted  rapidly. 

Alcohol  absorbs  several  volumes  of  this  gas,  and  the  solu- 
tion has  a  strong  odor,  commonly  called  spirits  of  hartshorn. 

The  dccojnposition  of  ammonia  is  effected  by  chlorine  and 
iodine. 

Exp.  Place  a  flask  of  ammonia  over  a  bottle  with  a  wide  mouth, 
containing  chlorine  gas.  The  gases  will  instantly  combine,  as  will  be 
seen  by  a  sheet  of  white  flame. 

Theory.  The  chlorine  unites  with  the  hydrogen  of  the  ammonia, 
forming  hydrochloric  acid ;  and  this  unites  with  some  undecomposed 
ammonia,  and  forms  hydrochlorate  of  ammonia,  and  will  be  deposited 
on  the  sides  of  the  flask  in  a  solid  state. 

Ammonia,  both  in  the  gaseous  and  liquid  formt  possesses 
decided  alkaline  properties* 

Exp.  Place  a  jar  of  ammoniacal  gas  on  a  plate  containing  vegetable 
infusion,  and  the  infusion  will  become  green. 

Uses.  Ammonia  is  used  in  the  arts  and  in  medicine.  In 
chemistry,  it  is  employed  to  neutralize  acids. 

Exp.  Colors  changed  by  acids  may  often  be  restored  by  ammonia. 
Hence  clothing  spotted  by  acids,  especially  woollen  clothes,  may  have 
the  color  restored  by  moistening  the  spots  with  the  liquid  ammonia. 

In  medicine,  it  is  used  as  a  tonic.     It  is  a  powerful   and 

*  This  introduces  to  us  a  new  class  of  bodies  —  the  alkalies.  Am- 
monia is  the  only  one  the  base  of  which  is  not  a  metal,  and  there  is 
still  some  doubt  whether  its  base,  nitrogen,  is  not  a  body  with  a  me- 
tallic base.  This  view  corresponds  best  with  the  general  analogy  of 
other  compounds.  The  alkalies  generally  have  the  following  prop- 
erties :  — 

1.  Caustic  to  the  animal  organs,  corrode  woollen  cloth,  and  are  gen- 
erally powerful  solvents  of  animal  matter. 

2.  Volatilized  by   heat,  but,  excepting  ammonia,  are  not  easily  de- 
composed by  it. 

3.  Combine  with  acids,  and  form  salts. 

4.  All  soluble  in  water. 

5.  Unite  with  oils,  and  form  soaps. 

6.  Taste  acrid,  very  different  from  acids. 

7.  Change  some  vegetable  blues  to  green.     This  last  property  is  a 
convenient  one  to  distinguish  them  from  acids.     One  of  the  best  tests 
of  acids  and  of  alkalies,  is  an  infusion  of  purple  cabbage,  which  is 
changed  to  red  by  acids,  and  to  green  by  alkalies. 


172  Carbon. 

grateful  stimulant,  producing  the  useful  effects  of  alcohol, 
without  its  injurious  consequences.  Ammonia  is  the  sub- 
stance employed  for  smelling-bottles.* 


SECT.  8.     CARBON. 


3.52  Water  =1. 
1. 


OKI-         v     •     $  by   vol.  100.  <j  C  3.52  Watc 

qU1V- 1  *  wgt      6.12.        SP-  F' 1  6.12  Hyd. 

Natural  History.  Carbon  is  one  of  the  most  important 
and  useful  of  substances.  Like  all  other  substances  of  ex- 
tensive utility,  it  is  widely  diffused.  It  exists  abundantly  in 
the  animal,  vegetable,  and  mineral  kingdoms.  The  greater 
part  of  the  substance  of  trees,  and  of  animal  bodies,  is  car- 
bon. It  is  rarely  found  quite  pure  in  nature,  and  cannot 
be  formed  perfectly  pure  by  art.  The  only  pure  carbon  is 
the  diamond. 

The  diamond  is  found  in  the  East  Indies  and  in  Brazil, 
S.  A.  They  generally  occur  in  alluvial  soils,  in  detached  crys- 
tals, the  primitive  form  of  which  is  the  regular  octahedron, 
but  sometimes  have  twenty-four,  and  even  forty-eight  faces. 
They  are  of  various  colors,  brown,  black,  red,  blue,  and  green, 
or  colorless  and  transparent ;  the  latter  are  the  most  valued. t 
The  diamond  M  the  hardest  body  in  nature.  It  is  a  powerful 
refractor  of  light,  a  property  which  led  Newton  to  predict  its 
combustion.  Lavoisier  first  proved  it  to  contain  carbon,  by 
exposing  it  in  oxygen  gas  to  the  solar  focus.  The  product 
was  carbonic  acid.  In  1807,  the  combustion  of  the  diamond 
in  oxygen  was  found  by  Allen  and  Pepys  to  be  attended  by 
the  same  results  as  that  of  charcoal.  Davy  confirmed  these 
results  by  comparing  the  combustion  of  the  diamond  with 
that  of  various  kinds  of  charcoal.  Another  proof  of  its  iden- 
tity is  the  fact,  that  diamond  converts  iron  into  steel  in  the 
same  manner  as  charcoal. 

*  To  prepare  a  smelling-bottle,  it  is  only  necessary  to  put  a  small 
quantity  of  quick  lime  and  hydrochlorate  of  ammonia  into  a  small  bot- 
tle, and  keep  it  corked  tight,  only  when  it  is  used. 

t  Diamonds  are  of  various  sizes ;  some  are  as  large  as  a  pigeon's 
egg,  and  the  value  increases  with  the  size,  in  a  very  rapid  ratio. 


Carbon.  173 

Uses.  The  diamond  is  the  most  valued  of  gems ;  used  in 
jewelry,  and  for  the  purpose  of  cutting  glass. 

The  other  kinds  of  carbon  are  the  following :  — 

Plumbago.  This  is  carbon  nearly  pure,  containing  four 
or  five  per  cent,  of  iron.  It  is  sometimes  called  black  lead, 
and  used  for  pencils,  crayons,  etc.  It  is  found  native  in 
primitive  formations,  and  is  next  to  the  diamond  in  purity. 

Anthracite  is  a  species  of  fossil  coal,  the  next  in  purity. 

Bituminous  coal  is  similar  to  the  preceding,  with  the  addi- 
tion of  bitumen,  when  the  bituminous  and  volatile  matter  is 
driven  off  by  heat ;  it  is  called  coke,  which  is  nearly  pure 
carbon. 

Peat  is  an  impure  kind  of  carbon,  containing  uncarbon- 
ized  vegetable  matter,  mixed  with  earthy  substances. 

Lampblack  is  a  kind  of  carbon  which  is  obtained  by  the 
combustion  of  turpentine,  pitch-pine,  camphor,  and  almost 
any  species  of  combustible  matter,  containing  carbon.  It  is 
deposited  from  flame  in  the  form  of  a  fine  black  powder. 
For  use  in  the  arts,  it  is  chiefly  made  by  turpentine  manufac- 
turers, from  the  refuse  resin.  This  is  burned  in  a  furnace, 
and  the  smoke,  carrying  up  the  carbon,  is  conducted  to  a 
room  hung  with  sacking,  upon  which  the  lampblack  is  depos- 
ited. It  is  collected  and  sold  without  further  preparation. 
It  is  used  extensively  as  a  paint  —  that  from  camphor  is  the 
best. 

Ivory  black  is  a  kind  of  lampblack  obtained  from  burning 
bones,  sometimes  called  animal  charcoal. 

Charcoal.  If  wood  be  burned  in  the  open  air,  nothing 
remains  but  ashes ;  but  if  the  air  is  mostly  excluded,  so  that 
it  undergoes  a  smothered  combustion,  a  black,  brittle  sub- 
stance remains,  called  charcoal,  which  is  nearly  pure  carbon 

Processes.  1.  For  the  common  purposes  of  fuel,  it  is  pre- 
pared by  forming  the  wood  into  a  conical  pile,  and  covering 
it  with  earth.  The  combustion  is  slow,  in  consequence  of 
the  small  quantity  of  air  which  is  admitted  ;  the  volatile  parts 
are  driven  off,  and  the  carbon  remains. 

2.  It  is  also  prepared  by  distillation  of  wood,  in  large  iron 
15* 


174 


Carbon. 


cylinders.  This  is  the  mode  of  preparing  it  for  the  manufac- 
ture of  gunpowder.  Beside  the  charcoal,  two  valuable  sub- 
stances, the  pyroligneous  acid  and  tar,  are  obtained. 

3.  But  the  purest  charcoal  is  prepared  by  charring  wood 
under  sand  or  melted  lead.  It  should  be  put  immediately 
into  bottles,  corked  tight,  to  exclude  the  air. 

Properties.  Carbon  is  a  black,  brittle,  shining,  inodorous 
substance,  easily  pulverized,  a  good  conductor  of  electricity, 
and  a  bad  conductor  of  caloric. 

It  is  tJie  hardest  substance  in  nature.  Common  charcoal 
appears  soft,  but  this  is  in  consequence  of  its  pores.  If 
rubbed  upon  glass,  it  will  scratch  it. 

It  has  the  property  of  absorbing  various  gaseous  bodies. 

F.fp.  Heal  a  piece  of  charcoal,  and  plunge  it  into  mercury  until 
cool,  then  place  it  under  a  glass  receiver  over  mercury.  In  the  course 
of  twenty-four  or  thirty-six  hours,  it  will  absorb  of  ammonia  90  times, 
the  volume  of  the  charcoal: 


Hydrochloric  acid, 85 

Sulphurous  acid,  .  .  ".  .  .  85 
Hydrosulphuric  acid,  ...  55 
Protoxide  of  nitrogen,  ...  40 
Carbonic  acid, 35 


Olefiant  gas, 35 

Carbonic  oxide,  ....  9.42 

Oxygen, !>.•,':> 

Nitrogen, 75 

Hydrogen, 1.75 


The  gases  will  be  given  up  again  by  heating  the  charcoal, 
or  partially  by  'plunging  it  into  water. 

Theory.  Tliis  power  cannot  be,  attributed  wholly  to  chemical  action, 
but  is  due  to  the  porous  texture  of  the  charcoal;  and  the  gases  appear 
to  be  absorbed  in  the  same  manner  that  sponges  and  other  porous 
bodies  absorb  liquids.  The  property  is  most  remarkable  in  the  com- 
pact varieties,  such  as  that  from  box- wood,  where  the  pores  are  numer- 
ous and  small.  By  reducing  it  to  powder,  this  power  is  diminished. 
In  plumbago,  and  in  the  diamond,  it  is  wholly  wanting. 

But  how  does  this  account  for  its  absorbing  more  ofone  gas  than  of 
another  ?  Chemical  affinity  has  doubtless  some  influence,  but  it  IB 
mostly  due  to  the  elasticity  of  the  gases.  Those  gases,  easily  converted 
into  liquids,  are  absorbed  in  greater  quantities  than  those  more  perma- 
nent; hence  vapors  are  absorbed  more  easily  than  gases,  and  liquids 
than  ether.  Hence,  too,  charcoal,  when  exposed  to  the  air,  or  other 
gases,  increases  in  weight.* 


*  The  increase  varies  with  the  kind  of  wood  from  which  it  is  made. 
According  to  the  experiment  of  Allen  and  Pepys,  charcoal  from  fir 
gains  13  per  cent. ;  lignumvitse,  9.6  per  cent.  :  that  from 

Box, 14.      I    Oak, 16.5 

Birch, 16.3    |    Mahogany,         .     .     18. 


Properties.  175 

The  absorption  is  the  most  rapid  during  the  first  twenty- 
four  hours  ;  it  absorbs  oxygen  from  the  air  more  rapidly  than 
nitrogen. 

Ii  also  absorbs  the  odoriferous  and  coloring  principles 
from  most  animal  and  vegetable  substances. 

I'.rj).  Pass  ink  through  pulverized  charcoal,  and  the  color  will  be 
discharged.  Red  wines,  ruin,  and  brandy,  may  be  rendered  colorless 
by  filtration  through  it. 

It  is  used  extensively  for  refining  sugar,  rind  for  preparing 
colorless  crystals  of  citric  acid,  and  other  vegetable  produc- 
tions. Stagnant  water,  and  most  animal  and  vegetable  sub- 
stances, in  a  putrescent  state,  will  be  cleansed  and  purified 
by  this  substance  ;  hence  its  use  to  purify  docks,  vessels,  etc. 
Putrescent  meat  is  purified  by  rubbing  it  with  charcoal ; 
and,  generally,  all  substances  subject  to  putrescence  may 
be  preserved  for  a  long  time,  by  surrounding  them  with 
charcoal. 

In  consequence  of  this  property,  it  is  used  in  medicine  as 
nri  antiseptic  in  putrescent  diseases.  Animal  charcoal  is  the 
best  for  these  purposes,  and  as  its  efficacy  depends  upon  Us 
power  of  absorption,  it  should  be  heated,  to  expel  all  the  gas, 
before  it  is  used,  or  kept  in  well-stopped  bottles  as  soon  as 
prepared. 

It  is  very  combustible.  It  requires  a  strong  heat  to  ignite 
it,  but  then  it  will  burn  for  a  long  time,  the  oxygen  of  the 
air  uniting  with  it  and  forming  carbonic  acid.*  In  conse- 
quence of  this  property,  it  is  one  of  the  most  useful  substances 
in  nature. 

It  is  the  most  durable  substance  known.  Grains  of  wljeat 
and  rye  charred  in  Herculaneum  by  the  volcanic  eruption, 
A.  D.  H),  were  easily  distinguished  from  each  other,  eighteen 
centuries  afterward  ;  an  arrow  head  has  been  charred,  and 
even  the  form  of  the  feather  preserved.  The  stakes  driven 
down  in  the  bed  of  the  Thames,  by  the  Britons,  to  prevent  the 
army  of  Julius  Caesar  from  passing  the  river,  were  discovered 
about  fifty  years  since,  and  were  all  charred  to  a  consider- 
able depth.  They  were  as  perfect  as  when  driven  ;  were 
made  into  knife-handles,  and  sold  as  antiques  at  a  high 
price.  Farmers  char  their  troughs  and  posts  to  prevent 
decay. 

*  Large  quantities  of  powdered  charcoal  often  ignite  spontaneously, 
owing,  doubtless,  to  the  small  quantity  of  potassium  which  is  gener- 
ally found  in  connection  with  it. 


176  Carbon. 

It  is  infusible. by  any  degree  of  heat,  except  that  from  a 
powerful  galvanic  battery  ;  and  in  this  case  there  is  reason  to 
doubt  whether  there  is  a  fusion  of  any  thing  but  of  some  im- 
purities in  the  carbon. 

Uses.  The  uses  of  carbon  have  already  been  stated,  and 
are  generally  well  known.  It  is  orie  of  those  substances 
which  are  indispensable  to  the  wants,  to  the  existence  of  our 
race ;  and  the  Creator  has  given  us,  in  its  character  and 
abundance,  the  most  decisive  proofs  of  his  wisdom  and 
benevolence. 

Carbon  possesses  extensive  powers  of  combination,  and 
forms  a  class  of  substances  of  great  and  permanent  utility  in 
chemistry,  the  arts,  and  the  common  business  of  life. 

.    Carbonic  Oxide.  Symb.COorC.  Equiv. 6.12  +  8=  1  i  I -2. 
Sp.gr.  0.9727,  air=l. 

History.  Discovered  by  Priestley  by  the  distillation  of 
charcoal  with  the  oxide  of  zinc ;  but  its  composition  wa- 
iir.-t  determined  by  Mr.  Cruickshank. 

Process.  The  best  and  most  convenient  mode  of  obtain- 
ing this  substance,  is  to  put  2  parts  of  well-dried  chalk, 
pulverized,  to  1  of  iron  filings,  into  a  gun-barrel,  and  raise 
the  temperature  to  a  red  heat.  The  gas  .may  then  be  col- 
lected over  water ;  it  may  be  obtained,  also,  by  heating  the 
oxides  of  several  of  the  metals  with  powdered  charcoal. 

Theory.  Chalk  is  composed  of  carbonic  acid  and  lime.  One  equiv- 
alent of  oxygen  contained  in  the  acid,  goes  to  the  iron,  and  converts 
the  acid  to  the  carbonic  oxide ;  oxide  of  iron  and  lime  remain,  or  CO* 
-f-  CaO  and  Fe  are  converted  into  FeO,  CaO,  and  CO. 

Properties.  A  colorless,  insipid  gas,  of  an  offensive  odor. 
It  is  highly  inflammable,  and  burns  with  a  pale  blue  flame 
when  a  lighted  taper  is  plunged  into  it,  but  does  not  support 
combustion.  A  mixture  of  1  part  of  oxygen  to  2  of  the 
gas  is  explosive ;  the  result  is  carbonic  acid.  It  is  destruc- 
tive to  animal  life  ;  an  animal  immersed  in  it  soon  dies. 
When  diluted  with  air,  it  causes  fainting  and  giddiness. 

Carbonic  Acid.    Symb.  C  +2O,  CO2  or  C.     Equiv.  6.12 

22.12.     Sp.  gr.  1.5239,  air=l. 
History.     Discovered  in  1757  by  Dr.  Black,  who  called 


^  Carbonic  Acid.  177 

it  fixed  air*  This  was  the  first  gas  known,  except  tlie 
atmosphere,  and  laid  the  foundation  of  pneumatic  chemistry. 
Natural  History.  Carbonic  acid  exists  very  abundantly 
in  nature,  generally  in  combination  with  lime,  forming  the 
carbonate  of  lime,  or  marble. 

Process.  It  is  obtained  by  the  combustion  of  the  diamond 
in  oxygen  gas,  or  by  burning  charcoal  in  the  air,  or  oxygen; 
but  it  is  more  easily  obtained  by  decomposing  some  of  the 
carbonates.  Take  pulverized  carbonate  of  lime  (marble  or 
chalk)  in  a  glass  retort,  and  pour  on  sulphuric  or  hydro- 
chloric acid,  diluted  with  five  or  six  parts  of  water,  and 
collect  over  water,  or  in  a  globe  receiver,  in  the  same  man- 
ner as  hypochlorous  acid  gas.t  (See  page  133.) 

Theory.  In  this  process,  the  sulphuric  acid  combines  with  the  lime, 
forming  the  sulphate  of  lime,  and  liberates  the  carbonic  acid.  SO3, 
CO2-fCaO  are  converted  into  SO3-fCaO  and  CO8. 

Properties.  It  is  colorless,  inodorous,  and  elastic,  requir- 
ing a  pressure  of  thirty-six  atmospheres,  540  Ibs.,  to  the 
square  inch,  to  condense  it  into  a  liquid  —  more  than  1J  times 
as  heavy  as  atmospheric  air,  and  hence  may  be  poured  from 
one  vessel  to  another,  like  water. 

It  is  neither  a  combustible  nor  a  supporter  of  combustion. 

Exp.  Into  ajar  of  carbonic  acid,  let  down  a  pendent  candle.  It  will 
be  extinguished  as  soon  as  it  reaches  the  gas,  or  it  may  be  poured  upon 
the  candle  from  a  vessel.  The  flame  does  not  cease  from  want  of  oxy- 
gen, since  four  measures  of  air  and  one  of  carbonic  acid  will  extin- 
guish flame  ;  hence  a  positive  influence  is  exerted  upon  it. 

It  is  rapidly  absorbed  by  water. 

Exp.  If  a  small  quantity  of  water  be  agitated  in  a  bottle  containing 
carbonic  acid  gas,  it  will  soon  absorb  it,  and  acquire  acid  properties. 

Recently-boiled  water  will  absorb  one  volume  of  the  gas  at  the  com- 
mon temperature  and  pressure,  but  increases  in  its  absorbing  power  in 
proportion  to  the  pressure  applied.  It  absorbs  twice  its  volume  when 
the  pressure  is  doubled,  three  times  its  volume  when  the  pressure  is 
trebled,  etc. 


*  Its  composition  was  first  demonstrated  synthetically  by  Lavoisier, 
who  obtained  it  by  the  combustion  of  charcoal  in  oxygen  gas.  Smith- 
son  Tennant  proved  its  composition  analytically  by  passing  the  vapor 
of  phosphorus  over  chalk,  heated  to  redness  in  a  glass  tube. 

t  If  intended  to  be  kept  long,  it  should  be  transferred  from  the  cis- 
tern in  bottles,  as  the  water  rapidly  absorbs  it. 


178 


Carbon. 


Water  may  be  acidulated  with  it,  by  employing  Woulfc's 
apparatus,  in  the  same  manner  as  wiih  hydrochloric  acid. 
(See  page  154.)  In  the  common  soda  fountains,  the  water 
is  confined  in  a  strong  brass  or  copper  vessel,  and  charged 
with  the  gas  by  a  forcing-pump.  The  pleasant,  pungent 
taste  and  sparkling  appearance  of  fermented  liquors,  so.h, 
and  Seidlitz  waters,  and  the  waters  of  many  mineral  springs, 
are  due  to  the  carbonic  acid  which  they  hold  in  solution. 
The  water  saturated  with  it  makes  a  pleasant  and  healthful 
drink. 

But  the  gas  escapes  on  exposure  to  air  and  heat.  Hence 
all  such  drinks  soon  become  insipid. 

If  the  pressure  is  removed,  the  escape 
of  gas  is  much  more  rapid. 

Exp.  Place  a  tumbler  of  water,  (Tip.  79,)  satu- 
rated with  this  gas,  under  the  receiver  a  of  an 
air-pump  b,  and  exhaust  the  air.  The  gas  will 
escape  so  rapidly  as  to  present  the  appearance 
of  boiling.  Any  of  the  fermented  liquors  will 
produce  similar  phenomena. 

If  the  water  saturated  with  the  acid 
be  rapidly  congealed,  the  frozen  water 
has  the  appearance  of  snow,  its  bulk 
being  greatly  increased  by  the  immense 
number  of  bubbles  formed  by  the  liber- 
ated gas. 

It  is  an  acidy  as  shown  by  chemical  tests. 

Erp.  Put  a  piece  of  litmus  paper  into  water  saturated  with  it,  and 
it  is  turned  red ;  but  by  heat,  or  exposure  to  the  air,  the  color  returns, 
owing  to  the  escape  of  the  acid. 

This  is  not  the  case  with  any  other  acid  ;  the  colors  they 
form  are  generally  permanent,  unless  changed  by  alkalies. 

The  best  test  of  carbonic  acid  is  lime  water t  which  is  ren- 
dered turbid  by  the  gas. 

Theory.  Carbonic  acid  unitejs  with  the  lime  which  the  water  holds 
in  solution,  and  forma  the  carbonate  of  lime,  which  is  soluble  in  water, 
and  is  precipitated  in  fine  powder.  This  gives  to  the  water  a  milky 
appearance.  If,  however,  you  continue  to  add  carbonic  acid,  it  will 
dissolve  the  carbonate,  and  the  water  will  become  clear  again,  carbon- 
ate of  lime  being  very  soluble  in  excess  of  carbonic  acid. 

Solidification  of  Carbonic  Acid.     It  has  lately  been  ascer- 


Carbonic  Acid.  179 

tained,  that  when  the  gaseous  carbonic  acid  is  subjected  to  a 
pressure  of  thirty-six  atmospheres,  it  is  condensed  into  a 
liquid,  and  at  -85°  into  a  solid  resembling  compact  snow.* 

Relations  to  Animal  Life.  Although  water  saturated  with 
carbonic  acid  proves  a  healthful  and  invigorating  drink,  the 
free  acid  cannot  be  taken  into  the  lungs  without  producing 
almost  instant  death  ;  in  fact,  the  glottis  closes  at  its  ap- 
proach, and  will  not  suffer  it  to  enter.  If  it  be  diluted  with 
air,  it  acts  upon  the  system  as  a  narcotic  poison ;  an  animal 
thrown  into  it  is  usually  suffocated. t  Carbonic  acid  is 
heavier  than  the  air,  and  hence  often  remains  in  wells  and 
deep  pits,  where  it  is  generated,  and  called  by  the  miners 
choki-damp.  Before  descending,  a  candle  should  be  let 
down,  and  if  it  will  not  burn,  life  cannot  ba  supported.  The 
acid  may  be  absorbed  by  pouring  down  large  quantities  of 
water  ;  it  may  be  partially  expelled  by  exploding  gunpow- 
der near  the  bottom  ;  or  it  may  be  drawn  up  with  large 
buckets. 

Production  of  Carbonic  Acid.  Causes  are  in  constant 
operation  to  form  carbonic  acid,  and  throw  it  off  into  the 

*  Mr.  Faraday  first  condensed  carbonic  acid  into  a  liquid  by  placing 
carbonate  of  ammonia  in  one  end  of  a  strong  glass  tube,  bent  twice  at 
right  angles,  and  sulphuric  acid  in  the  other  end,  which  is  sealed  her- 
metically. When  the  acid  is  poured  upon  the  ammonia,  it  combines 
with  it  and  liberates  the  gas,  which,  by  the  pressure,  is  condensed  ; 
but  this  process  is  attended  with  much  danger,  from  the  bursting  of 
the  tube.  A  safer  method  has  been  contrived  by  Thillorier,  in  which 
tin-  gas  is  condensed  in  a  strong  metallic  cylinder.  By  allowing  the 
liquid  acid  to  escape  through  the  stop-cock,  it  expands  so  rapidly  as  to 
become  frozen,  owing  to  the  absorption  oftits  sensible  caloric.  A  re- 
duction of  temperature  to  -162°  is  said  to  have  been  produced  by  this 
means  The  solid  acid  thus  formed  is  about  the  weight  of  carbonate 
of  magnesia,  perfectly  white,  and  of  a  soft,  spongy  texture.  "It  evapo- 
rates so  rapidly  that  mercury,  and  even  alcohol,  (sp.  gr.  .820,)  are  frozen. 
According  to  the  experiments  of  Mitchell,  of  Philadelphia,  the  greatest 
cold  produced  by  the  solid  acid  in  the  air  was -109°,  and  under  an 
exhausted  receiver  -136°.  The  pressure  at  32°  was  36  atmospheres, 
at  6U°,  60  atmospheres,  and  at  86°,  72  atmospheres,  or  1290  Ibs.  to  the 
square  inch.  When  obtained  in  a  liquid  form  in  a  glass  tube,  it  is 
colorless  and  extremely  fluid  In  attempting  to  open  the  tubes  at  one 
end,  they  uniformly  burst  into  fragments,  with  violent  explosions. 

t  Caution.  This  gas  is  always  produced  in  burning  charcoal ;  and 
hence  the  danger  and  criminality  of  placing  pans  of  hot  coals  in 
sleeping  apartments,  or  in  rooms  not  ventilated  by  a  chimney.  The 
acid  gradually  mixes  with  the  air,  causing  drowsiness,  and  even  death, 
before  the  person  can  escape.  Every  year  adds  new  proofs,  in  the  loss 
of  many  lives,  to  the  folly  and  danger  of  such  practices. 


180  Carbon. 

atmosphere.  It  is  evolved  in  great  quantities  from  the  earth, 
from  ordinary  combustion,  and  by  the  respiration  of  animals. 
In  the  two  last  cases,  the  oxygen  of  the  air  is  consumed,  and 
carbonic  acid  takes  its  place;  hence  we  should  expect,  if 
there  were  nothing  to  counteract  this  process,  that  the  whole 
atmosphere  would,  in  time,  be  rendered  unfit  to  support 
respiration  ;  but  not  more  than  T(JQV  Part  °f  tne  atmosphere 
is  carbonic  acid.  In  places  near  cities,  or  where  it  is  evolved 
from  the  earth,  the  proportion  may  be  greater.  This  ten- 
dency, however,  may  be  counteracted  by  the  vegetaUe  kipg- 
dom.  During  the  daytime,  plants  absorb  carbonic  acid,  de- 
compose it,  retain  its  carbon,  and  throw  off  its  oxygen.  In 
the  night,  the  process  is  reversed;  oxygen  is  consumed,  and 
carbonic  acid  is  thrown  off;  but  more  of  oxygen  is  emitted 
in  the  daytime  than  is  consumed  in  the  night;  more  carbonic 
acid  also  is  consumed  during  the  day  thun  is  given  off  dur- 
ing the  night.  The  balance  from  this  process  is  needed  to 
meet  the  demands  of  the  anima)  kingdom,  which  const;  ntlv 
consumes  oxygen,  and  generates  carbonic  acid  in  the  pr- 
of respiration.  Thus  the  equilibrium  of  the  atmosphere  is 
preserved,  and  both  kingdoms  flourish  together. 

Ezp.  That  carbonic  acid  is  given  off  in  renpiration,  may  be  show  t, 
by  breathing  with  a  quill  through  limo  \\.it, -r,  which  will  become  tur- 
bid. This  tact  enables  us  to  understand  the  process  of 

Respiration.  The  blood,  in  its  progress  through  the 
tem,  becomes  filled. with  carbon,  which  gives  to  it  a  dark 
color.  When  it  passes  into  the  lungs,  the  air  is  brought  in 
contact  with  it;  the  carbon  unites  with  the  oxygen,  fon 
carbonic  acid,  which  is  expelled,  and  the  blood  is  chan-jrd 
to  a  bright  red  ;  it  is  now  fitted  to  nourish  the  system.  Some 
suppose  that  the  oxygen  enters  into  the  blood,  and  that  the 
combination  takes  place  during  the  course  of  circulation  ;  but 
whichever  theory  be  adopted,  carbonic  acid  is  thrown  off, 
and  oxygen  is  consumed.  Hence,  in  crowded  assemblies, 
great  quantities  of  this  gas  are  formed,  and,  as  a  consequence, 
dulness  and  fainting  often  ensue.  Hence,  also,  the  neces- 
sity of  having  large  public  rooms  well  ventilated. 

Bichloride  of  Carbon  (Symb.  C«C1.  Equiv.  12.24  -f  35.42  =  47.60) 
was  discovered  by  M.  Julin.  It  occurs  in  small,  soft,  adhesive  fibres, 
of  a  white  color,  of  a  peculiar  odor,  resembling  spermaceti,  and  is  taste- 
less ;  burns  with  a  red  flame,  emitting  much  smoke,  and  fumes  of  hy- 
drochloric acid  gas. 

Protochloride  of  Carbon.  Symb.  CC1.  Equiv.  6.12  -f-  35.42  =41 .54. 
Jt  is  obtained  by  passing  the  vapor  of  perchloride  of  carbon  through  a 


Compounds  of  Carbon.  181 

heated  glass  tube,  filled  with  fragments  of  rock  crystal,  to  increase  the 
heated  surface.     It  is  a  limpid,  colorless  liquid  j  density,  1 .5526. 

|-  Chloride  of  Carbon.  Symb.  C4C15.  Equiv.  24.48  -f  177.1  =  201.58. 
Discovered  by  Liebig,  and  sometimes  called  the  new  chloride  of 
Liebig;  obtained  by  boiling  chloral  with  a  solution  of  lime,  potassa,  or 
baryta.  It  is  a  limpid,  colorless  liquid,  similar  in  odor  and.  appearance 
to  the  oily  fluid  which  chlorine  forms  with  olefiant  gas  ;  density,  1.48  : 
boils  at  141°  Fahr. 

Per  chloride  of  Carbon.  Symb.  C8CR  12.24  -f  106.26  =  118.5.  Dis- 
covered by  Faraday.  When  olefiant  gas  is  mixed  with  chlorine,  com- 
bination takes  place  between  them,  and  an  oil-like  liquid  is  formed, 
consisting  of  carbon,  hydrogen,  and  chlorine.  Expose  this  liquid,  in  a 
jar  of  chlorine,  to  the  solar  rays,  and  hydrochloric  acid  is  set  free,  and 
the  chloiine  unites  with  the  carbon. 

Properties.  At  common  temperatures,  it  is  a  colorless,  transparent 
solid,  of  an  aromatic  odor,  resembling  that  of  camphor ;  fuses  at  320°, 
and  boils  at  300°. 

Cliloro-carbonic  Add.  Symb.  O  -|-  C  -f  Cl.  Equiv.  8  -f-  6.12  -}-  35.42. 
=  4i>.54.  This  singular  compound  of  oxygen,  chlorine,  and  carbon, 
affords  a  somewhat  unusual  instance  of  two  acidifying  principles 
uniting  with  one  base  to  form  an  acid.  It  was  discovered  by  Dr. 
Davy,  who  called  it  Phosgene  gas.  It  is  formed  by  exposing  equal 
volumes  of  chlorine  and  carbonic  oxide  to  the  solar  rays,  when  rapid 
but  silent  combustion  takes  place,  and  they  contract  to  one  half  their 
volume. 

Properties.  A  colorless  gas,  with  a  strong  odor;  reddens  litmus  pa- 
per, and  combines  with  fou/  times  its  volume  of  ammoniacal  gas.  Wa- 
ter and*  several  of  the  metals  decompose  it. 

Chloral  (Symb.  C9C16O4.  Equiv.  299.60)  is  a  new  compound  of 
carbon,  oxygen,  and  chlorine,  discovered  by  Liebig,  and  prepared  by 
the  mutual  action  of  alcohol  and  chlorine.  It  is  a  colorless,  transparent 
liquid,  of  a  penetrating,  pungent  odor,  nearly  tasteless,  oily  to  the 
touch  ;  density,  1.502,  and  boils  at  201°. 

Pniodide  of  Carbon  was  discovered  by  Serullas,  and  is  obtained  by 
mixing  an  alcoholic  solution  of  pure  potassa  and  of  iodine.  It  forms 
crystals  of  a  pearly  lustre,  sweet  to  the  taste,  and  of  a  strong,  aromatic 
odor,  resembling  saffron. 

The  Protiodide  is  formed  by  distilling  a  mixture  of  the  preceding 
compound  with  corrosive  sublimate.  It  is  a  liquid  of  a  sweet  taste,  and 
penetrating,  ethereal  odor. 

Bromide  of  Carbon.  Formed  by  mixing  1  part  of  periodide  of 
carbon  with  2  of  bromine :  two  compounds  are  formed,  the  bromide 
of  carbon  and  the  sub-bromide  of  iodine;  the  latter  is  removed  by  a 
solution  of  caustic  potassa.  It  is  liquid  at  common  temperatures,  but 
crystallizes  at  32°  Fahr. ;  sweet  to  the  taste,  and  of  a  penetrating,  ethe- 
real odor ;  distinguished  from  the  protiodide  by  the  vapor  which  it  emits 
on  exposure  to  heat. 

16 


182  Carbon  and  Hydrogen. 

Carbon  and  Hydrogen. 

Two  compounds  of  carbon  and  hydrogen  have  been  known 
for  some  time,  but 'of  late  the  number  has  been  increased  to 
at  least  twelve. 

Dicarburet  of  Hydrogen.  Symb.  C  +  2H  or  CH*.  Equiv. 
6.12  +  2  =  8.12.  Sp.  gr.  0.5593,  air  =  1. 

History.  This  substance  is  generally  known  under  the 
name  of  light  carbureted  hydrogen.  The  names  hrury  in- 
flammable air,  the  inflammable  air  of  niar.</u.<,  and  hydro- 
carburet,  have  also  been  applied  to  it;  but,  taking  carbon  u 
the  electro-negative  element,  it  is  more  agreeable  with  the 
principles  of  nomenclature  to  call  it  bdirurbunt  vf  hi/do 
Dal  ton  first  ascertained  its  real  nature,  but  it  was  subse- 
quently examined  by  Davy,  Thompson,  and  II*  nry. 

Process.  This  gas  is  formed  naturally  by  the  decomposi- 
tion of  vegetable  matter  in  marshes.  It  may  be  obtained  by 
inverting  a  receiver  in  almost  any  stagnant  pool,  and  stirring 
the  sediment  at  the  bottom.  In  this  state  it  contains  one 
twentieth  part  of  carbonic  acid,  and  one  fifteenth  of  nitrogen  ; 
the  former  may  be  removed  by  lime  water  or  pure  pot 
This  is  the  best  mode  to  obtain  the  pure  gas. 

It  is  formed  also  by  the  distillation  of  mineral  coal,  con- 
taining carbonic  acid  and  olefiant  gas;  the  former  may  1  c 
removed  by  lime  water,  the  latter  by  chlorine. 

Properties.  Colorless,  tasteless,  and  nearly  inodorous. 
Water  absorbs  ^  of  its  volume.  It  extinguishes  all  burning 
bodies,  but  is  highly  combustible.  It  burns  in  a  jet  with  a 
yellow  flame,  brighter  than  hydrogen  ;  destructive  to  animal 
life  when  respired;  partially  decomposed  by  a  very  intcn.-r 
heat. 

Erp.  Mixed  iritli  rnthrr  more  than  twice  its  volume  of  oxygen,  it  is  rr- 
plosire  ;  exactly  two  volumes  of  oxygen  are  consumed,  and  the  prod- 
ucts are  carbonic  acid  and  water. 

Erp.  Mixed  with  chlorine,  and  exposed  to  the  solar  light,  it  is  de- 
composed, and  hydrochloric  and  carbonic  acids  are  formed;  though  the 
products  will  depend  upon  the  quantity  of  chlorine. 

Olefiant  Gas,  or  f  Carburet  of  Hydrogen.  Symb.  2C  -f- 
2H.  Equiv.  12.24  +2  =  14.24.  Sp.  gr.  0.9808,  air  =  1. 


Carbon  and  Hydrogen.  183 

History.  Discovered  in  1796  by  some  associated  Dutch 
chemists,  who  called  it  oljiant  gas  from  its  forming  an  oil- 
like  liquid  with  chlorine.  ,  It  has  been  called  hydurct  of  car- 
bon, bicarbureted  or  pcrcarburefed  hydrogen ;  but  J  carburet 
of  iiydrogcn  accurately  designates  its  composition,  and  is,  on 
this  account,  preferable, 

Process.  Mix  in  a  large  retort  1  measure  of  alcohol  with 
2  of  concentrated  sulphuric  acid,  and  apply  the  heat  of  a 
spirit  lamp.  The  mixture  soon  turns  black,  and  rises  up  in 
the  retort ;  the  gas  is  rapidly  disengaged,  and  may  he  col- 
lected over  water  or  mercury ;  carbonic  and  sulphuric  acids 
are  formed  during  the  process,  and  may  be  separated  by  pure 
potassa  or  lime  water. 

Theory.  Alcohol  is  a  compound  of  "defiant  gas  and  water.  The 
sulphuric  acid  unites  with  the  water,  and  the  gas  is  evolved.  C2H3O 
and  SO3  are  converted  into  SO3,  HO,  and  C2H2.  At  the  commence- 
ment of  the  process,  ether  is  formed,  which  differs  from  alcohol  by  hav- 
ing 2  equiv.  of  olefiant  gas  combined  with  water,  while  alcohol  has  but 
1.  The  ether  is  condensed  in  the  cistern. 

Properties.  It  is  a  colorless,  tasteless  gas,  and  has  scarcely 
any  odor  when  pure.  Water  absorbs  £  of  its  volume.  It 
extinguishes  a  lighted  taper  when  immersed  in  it,  and  there- 
fore does  not  support  respiration.  It  burns  with  a  clear,  white 
light. 

Mixed  with  oxygen,  it  is  highly  explosive. 

Exp.  Mixed  with  oxygon  in  the  proportions  of  1  volume  of  the  gas 
to  :>  of  oxygen,  and  kindled  by  flame,  or  the  electric  spark,  it  explodes 
with  great  violence.  This  may  be  shown  by  the  gas  pistol.  There  is, 
however,  much  danger  of  bursting  the  pistol;  glass  vessels  should 
not  be  employed  to  explode  it. 

Exp.  Bubbles  of  the  mixture  may  be  passed  up  through  the  water 
of  the  cistern,  and  exploded  upon  the  surface  ;  but  care  should  be  taken 
that  the  fire  is  not  communicated  to  the  vessel  containing  the  mixture, 
through  the  bubbles  as  they  rise. 

It  is  decomposed  by  heat.  By  passing  it  through  a  porce- 
lain tube  at  a  low  red  heat,  charcoal  is  deposited,  and  the 
bicarburet  evolved,  which,  at  a  white  heat,  is  also  decom- 
posed. It  is  also  resolved  into  hydrogen  and  carbon  by  a 
succession  of  electric  shocks. 

Action  of  Chlorine.  When  2  volumes  of  chlorine  and  1 
of  olefiant  gas  are  mixed  and  ignited,  they  burn  rapidly, 


184  Carbon.  — Gas  Lights. 

and  form  hydrochloric  acid,  while  the  carbon  is  deposited  • 
but,  if  the  gases  remain  at  rest,  they  slowly  combine,  and  form 
an  oily  liquid,  of  a  yellow  color,  called  chloride  of  hydro- 
carbon. 

Carburet  of  Hydrogen,  EtJurint,  (Symb.  4C  +  4H.     Equiv 


tCar 
=  2 


Faraday  in  the  process  of  compressing  oil  gas  into  strong  copper 
globes,  for  the  supply  of  portable  gas.  It  is  a  highly  volatile  liquid, 
the  lightest  liquid  body  known.  At  00°,  it  is  exceedingly  combustible, 
and  burns  with  a  brilliant  flame. 

|  Carburet  of  Hydrogen  (Symb.  6C-J-3H.  Equir.  36.72  +  3  = 
39.72.  Sp.  gr.  0.85)  was  obtained  by  Faraday  from  the  same  oil  gas 
liquid  which  yielded  etherine.  At  common  temperatures,  it  is  a  color- 
less, transparent  liquid,  smells  like  oil  gas,  with  a  slight  odor  of  almonds. 
It  is  highly  combustible,  and  form*  with  oxygen  a  powerful  detonating 
mixture. 

Parrajfine  is  a  compound  of  carbon  and  hydrogen,  obtained  by  the 
distillation  of  the  petroleum  of  Rangoon,  and  also  by  that  of  tar  de- 
rived from  beech  wood.  It  is  a  fatty  substance,  without  taste  or  odor, 
and  burns  with  a  pure  white  flame. 

Eupione  differs  from  the  preceding  compound  only  in  containing  a 
•mailer  portion  of  carbon.  It  is  obtained  by  distillation  of  the  tar 
derived  from  bones  or  horns.  It  is  a  tasteless,  inodorous  liquid,  similar 
to  oils,  but  as  limpid  as  alcohol. 

Naphtha  (Symb.  6C  +  5H.  Equiv.  36.72+  5  =  41.72.  Sp.  gr. 
0.753)  is  obtained  from  coal  tar  by  distillation.  It  is  a  volatile,  limpid 
liquid,  of  a  strong,  peculiar  odor,  and  generally  of  a  light  yellow  color. 
It  is  very  inflammable,  burning  with  a  white  name  and  much  smoke. 
It  is  used  to  preserve  potassium. 

Naphthaline  (Symb.  C'°H4.  Equiv.  61 .2-}- 4  =65.2)  is  obtained  in 
the  same  manner  as  the  preceding  compound.  It  is  a  white,  crys- 
talline solid,  heavier  than  water,  has  an  aromatic  pungent  taste,  ;m<l 
faintly-aromatic  odor.  With  sulphuric  acid,  it  forms  a  compound,  first 
described  by  Faraday  in  l.-2(i,  under  the  name  of  sulplio-naphthuitc  uciil, 
which  has  a  bitter  taste  and  acid  properties. 

ParanaphthuHne  (Symb.  C15He.  Equiv.  91 . 8 -f  6  =  1)7.8)  is  allied 
to  the  preceding,  and  obtained  from  coal  tar. 

Idridline  is  also  similar,  and  obtained  from  a  mineral  in  the  quick- 
silver mines  at  Idria,  in  Carniola. 

Camphene  and  Citrent.  Symb.  C'°H8.  Equiv.  61.2 +  8  =  GO .2. 
Camphene  is  the  basis  of  camphor  ;  colorless,  volatile,  and  inflammable  ; 
odor  like  the  oil  of  turpentine.  Citrene  is  almost  the  sole  ingredient 
of  the  oil  of  lemons. 

Gas  Light*. 

History.  The  gas,  now  so  generally  employed  for  the 
purpose  of  lighting  cities,  is  probably  a  mixture  of  several  of 


Gas  Lights.  185 

the  preceding  substances,  composed  mostly,  however,  of 
olcfiant  gas.  This  gas  was  first  employed  for  the  purposes  of 
illumination  by  Dr.  Clayton,  in  1739,  but  was  soon  given  up 
for  more  than  sixty  years.  The  subject  was  investigated, 
about  fifty  years  since,  by  I-.Ir.  Murdock  ;  and  since  that  time 
gas  lights  have  come  into  general  use,  both  in  Europe  and 
America.  The  gas  was  obtained  chiefly  from  the  distillation 
of  co:tl;  but  that  obtained  from  oil  (spermaceti  is  the  best)  is 
^much  purer,  and  possesses  a  greater  illuminating  power. 
Gas  from  rosin  is  about  equal  to  that  from  oil. 

Prnccfs.  When  oil  is  used,  several  large  cylindrical  cast- 
iron  retorts  are  laid  across  a  furnace,  and  partially  filled  with 
brick  and  bits  of  iron,  to  increase  the  heated  surface.  The 
oil  is  contained  in  a  reservoir,  and  conveyed  to  the  retorts  by 
separate  tubes.  When  the  retorts  are  heated  to  the  proper 
temperature,  the  oil  is  admitted  by  a  stop-cock,  in  a  small 
stream,  so  that  it  is  immediately  decomposed,  and  the  gas 
passes  out  of  the  retorts  by  other  tubes,  running  into  a  large 
one,  which  conveys  it  to  the  gasometer.* 

When  coal  is  used,  the  process  is  similar :  the  gas  needs 
to  be  purified  by  passing  it  through  lime  water,  to  deprive  it 
of  carbonic  acid  and  other  impurities,  which  give  it  a  very 
<!is:igreeable  odor;  112  pounds  of  coal  yield  from  450  to  500 
cubic  feet  of  gas;  sp.  gr.  0.450  to  0.700;  and  ^  a  cubic  foot 
of  gas  per  hour  is  equivalent  to  a  candle,  six  to  the  pound, 
burning  during  the  same  time.  But  oil  gas,  though  much 
more  expensive,  possesses  nearly  twice  the  illuminating  power 
According  to  Henry,  it  requires  vessels  and  tubes  of  but  half 
the  size.  20  cubic  feet  of  coal  gas,  or  10  of  oil  gas,  is  equal 
to  a  pound  of  tallow. t 

Portable  Gas.  In  consequence  of  the  greater  cheapness 
of  gas  lights,  as  compared  with  candles  and  oil,  it  seemed 

*  The  gasometer  is  made  of  iron,  in  some  cases  40  feet  in  diameter 
and  20  feet  high,  containing  20,000  cubic  feet.  This  is  immersed  in 
a  vat  containing  water,  and  the  air  permitted  to  escape  by  a  valve  in 
the  top.  When  it  is  filled  with  water,  the  gas  from  the  large  pipe  is 
conducted  to  the  bottom,  and  passes  up  through  the  water  into  the 
gasometer,  which  rises  as  fast  as  it  is  filled.  The  gas  is  now  con- 
veyed in  a  cast-iron  pipe,  laid  under  ground,  to  which  small  pipes  are 
attached,  branching  off  to  every  part  of  the  city  where  it  is  wanted. 

t  Coal  gas  costs  about  two  thirds  as  much  as  oil  gas,  and  about  one 
fifth  as  much  as  spermaceti  candles. 

16* 


1 86  Carbon. — Fire-Damp. 

desirable  to  contrive  some  method  by  which  it  could  be  made 
portable.  This  object  has  been  effected  by  what  are  called 
portable  lamps.  The  gas,  by  means  of  a  forcing-pump,  is 
compressed  into  strong  brass  globes,  and  ignited  as  it  esr 
through  an  aperture  which  is  furnished  with  a  stop-cock  to 
regulate  the  quantity.  These  can  be  carried  about  like  com- 
mon oil  lamps.  For  this  purpose,  the  gas  obtained  from  rosin 
is  empldyed. 

Fire-Damp.     This  term  is  applied  to  several  gaseous  com- 
pounds of  carbon  and  hydrogen,  which  are  produced  in  the 
mines  of  bituminous  coal.     It  is  mostly  light  iiirhur<ti.il  hy- 
drogen, and  is  produced  by  the  decomposition  of  the  water 
by  the  coal.     It  issues  from  various  parts  of  the  coal  bed-,  in 
such  quantities  as  to  render  the  whole  atmosphere  of  the  n 
explosive,  and  often  irrespirable.     Hence  the  miners 
exposed  to  frequent  explosion,  and  to  suffocation.     Mi, 
plosions  have  occurred  in  the  coal  mines  of  i 
older  mines  extend  miles  under  the  ground,  and,  in  some 
S    are  several   hundred   feet   deep.     As   the  gases  are 
lighter  than  the  air,  they  rise  and  mingle  with  the  air 
the  top,  and  gradually  descend  until  they  reach  the  ni' 
lamp,   when  the  whole  is  instantly    exploded.*      In    < 
quence  of  the  great  expense  of  human  life,  and  the  co: 
fear  of  the  miners,  Sir  H.  Davy  undertook  the  in  vest  ij/ 
of  the  subject  for  the  purpose  of  inventing  some 
safety.     He  went  with  the  miners  into  the  region  of  the  fire- 
damp, obtained  specimens  of  the  gas,   and  subjected  it   to 
chemical  examination.     He  found  that  the  most   exp! 
mixture  was  1  part  of  gas  to  7  or  8  of  air;  5  or  <>  voimi 
air  would  explode  but  feebly,  and  above  14  volumes  of  air  to 
1  of  gas  did  not  explode  at  all.     It  was  also  found  that  it  re- 
quired the  heat  of  flame  to  explode  it.     Iron  at  a  red  heat, 
and  even  at  a  white  heat,  would  not  affect  it.     But  the  fact 
which  led  immediately  to  the  invention  of  the  safity  l(nnj), 
had  been  observed  by  Dr.  Wollaston,  that  "an  explosive  ;///>- 
ture  cannot  be  kindled  through  a  glass  tube  so  narrate  as  }  of 
an  inch  in  diameter."     It  was  also  noticed  that  the  mixture 
could  not   be  exploded  through  fine  wire  sieves,  or   gauze 
wire,  which  acts  on  the  same  principle  as  longer  tubes. 

*  In  1812,  an  explosion  occurred  in  Felling  colliery,  in  Northumber- 
land, by  which  ninety-two  men  lost  their  lives.  The  explosion  was 
heard  three  or  four  miles  ;  thirty-two  persons  only  were  saved  alive. 
In  1815,  a  similar  occurrence  happened  at  Durham,  and  destroyed 
fifty-seven  persons ;  and  in  another,  twenty-two  lost  their  lives. 


Carbon.  —  Safety  Lamp. 


187 


Fig.  8O. 

Exp.  Place  the  gauze 
wire  a  (Fig.  80)  over  a  jet 
-of  the  gas;  the  flame  may 
be  pressed  down,  and  will 
not  pass  through  the  wire. 

Exp.  Let  a  stream  of 
the  gas  pass  through  the 
wire  c  ;  the  g;is  may  be  ig- 
nited on  the  top  of  the 

wire,  but  will  not  communicate  through  it  to  the  tube          Fig.  81, 
b.    The  same  is  true  of  flame,*  by  whatever  substance 
it  is  produced.     The  wires  conduct  off  the  heat,  so 
lint    they  do  not   gain  the    temperature   requisite  to 
ignite    the    gas. 

Safety  Lamp.  This  consists  simply  of  a 
common  lamp,  a,  (Fig.  81,)  with  a  gauze  wire, 
6,  surrounding  the  flame.  The  wire  should 
have  at  least  625  apertures  to  the  square  inch. 
Furnished  with  this  lamp,  the  miners  can 
enter  the  mines  in  perfect  safety  from  explo- 
sion, but  are  exposed  to  suffocation,  when 
there  is  not  sufficient  oxygen  in  the  mines  to 
support  the  combustion  of  the  oil. 

To  enable  the  miner  to  escape  from  the 
mine  when  the  atmosphere  becomes  such 
as  to  extinguish  the  flame  of  the  lamp,  a 
platinum  coil  may  be  inserted  around  the 
wick.  Thus,  in  the  lamp  6,  (Fig.  82,)  let 
a  platinum  coil  a  be  inserted  around  the 
wick ;  when  the  flame  ceases,  the  combus- 
tion will  continue  slowly  for  hours,  so  as 
to  heat  the  platinum  red-hot.  This  will 
give  sufficient  light  to  enable  the  miner  to 
escape. 

This  is  founded  on  the  fact,  that  plati- 
num wire  or  foil  will,  if  heated,  cause  certain  gases  to  com- 
bine gradually,  with  the  production  of  a  red  heat,  but  with- 
out flame. 

Exp.  Pour  a  small  quantity  of  ether  into  the  lamp,  and,  having 
heated  the  coil  of  platinum,  plunge  it  into  the  ether  ;  the  heat,  of  the 
wire  will  cause  the  vapor  of  ether  and  the  oxygen  of  the  air  to  com 

*  The  flames  of  candles,  lamps,  gas  lights,  &c.,  are  hollow,  as  may 
be  shown  by  holding  a  plate  of  glass  over  them.  Flames  formed  by  a 
mixture  of  oxygen  with  the  combustible  are  solid  ;  hence  the  use  of 
the  blowpipe,  bellows,  &c.,  to  render  the  flame  solid  and  increase  the 
heating  power. 


188  Carbon  and  Nitrogen. 

bine,  BO  as  to  keep  the  wire  red-hot,  and  sometimes  even  at  a  white 
heat,  when  the  ether  will  burst  into  a  flame 

Carbon  and  Nitrogen. 

Bicarburct  of  Nitrogen,  or  Cyanogen.  Symb.  NC2  or  Cy 
Equiv.  14.15  +  12.24  =  26.39.  Sp.  gr.  1.804,  air=  1. 

History.  This  gas  was  discovered  in  1815,  by  Gay  Lussac. 
It  is  sometimes  called  nituret  of  carbon,  but  bicarbunt  of 
nitrogen  expresses  definitely  its  composition. 

Process.  It  is  obtained  from  the  bicyanuret  of  mercury, 
by  heating  the  salt  in  a  small  glass  retort,  with  a  spirit  lamp. 
The  retort  should  be.  covered  with  lute,  to  prevent  its 
melting.  At  a  red  heat,  it  is  decomposed.  The  cyanogen 
passes  over  in  the  form  of  a  gas,  and  the  mercury  is  sublimed, 
and  remains  in  the  neck  of  the  retort  in  small  globules. 
Collect  over  mercury  or  air. 

Properties.  This  gas  is  colorless,  with  a  strong,  pungent 
odor;  not  a  supporter  of  combustion,  but  burns  itself  with 
a  beautiful  purple  flame,  resembling  the  peach  blossom 
Water,  at  the  common  temperature  and  pressure,  al>s«>r 
times  its  volume,  and  alcohol  25  times  its  volume.  At  the  tem- 
perature of  45°,  and  under  a  pressure  of  3.G  atmospheres,  it  is 
condensed  into  a  limpid  liquid,  but  resumes  the  ga.~ 
state  when  the  pressure  is  removed.  The  most  remark  ihlr 
chemical  property  of  this  substance  is,  that  it  acts  like  a 
simple  body  in  most  of  its  combinations,  forming  substances 
consisting  of  three  elementary  bodies,  analogous  to  those 
formed  in  other  cases  by  two. 

Cyanic  Acid  (Symb.  Cy  +  O.  Equiv.  26.39  +8  =  34.39) 
may  be  obtained  by  exposing  cyanuric  acid  to  a  dull  red  heat. 
It  has  a  penetrating  odor,  pungent,  and  caustic  to  the  skin, 
producing  great  irritation  of  the  eyes;  very  volatile,  giving 
off  an  inflammable  vapor. 

Fulminic  Acid.  This  is  isomeric  with  the  preceding,  i.  e., 
identical  in  composition,  but  possessed  of  different  properties. 
It  is  called  fulminic  because  its  compounds  of  mercury  and 
silver  are  highly  explosive. 

Cyanuric  Acid  (Symb.  Cy3Q6H3.  Equiv.  130.17)  was 
obtained  by  Serullas  by  gently  boiling  bichloride  of  cyanogen 


Compounds  of  Carbon.  189 

in  water:  cyanuric  and  hydrochloric  acids  are  the  results. 
The  hydrochloric  is  removed  by  evaporation,  and  the  cyan- 
uric  deposited,  on  cooling,  in  oblique  rhomboidal  crystals. 
The  crystals  are  further  purified  by  solution  and  evaporation. 
Paracyanuric  Acid  is  identical  in  composition  with  the 
preceding,  but  different  in  properties;  it  results  from  the 
spontaneous  decomposition  of  hydrous  cyanic  acid. 

Chloride  of  Cyanogen.  Symb.  Cy  -f  Cl.  Eq.  61 .81 .  First  obtained 
in  a  pure  stale  by  Sorullas,  in  1829,  by  exposing  bicyanuret  of  mercury 
in  powder,  and  moistened  with  chlorine  gas  in  a  well-stopped  vial.  It 
congeals  at  zero  in  needle-shaped  crystals  ;  is  liquid  between  5°  arid 
10°,  but  above  this  it  is  a  colorless  gas,  of  a  very  offensive  odor,  irri- 
tating to  the  eyes,  corrosive  to  the  akin,  and  highly  injurious  to  ani- 
mal life. 

liichlor'uh  of  Cyanogen.  Symb.  Cy-f-2Cl.  Eq.  97.23.  Discovered 
also  by  Serullas,  by  putting  155  grains  of  pure  hydrocyanic  acid  into  a 
bottle  containing  sixty  cubic  inches  of  dry  chlorine,  and  exposing  it  to 
the  solar  rays.  The  acid  is  vaporized,  and,  in  the  course  of  a  few 
hours,  a  colorless  liquid  is  formed  on  the  surface  of  the  bottle,  gradu- 
ally growing  thicker,  until,  in  the  space  of  twenty-four  hours,  it  sets 
into  a  white  solid,  with  shining  crystals.  This  is  the  bichloride  of 
cyanogen.  It  is  exceedingly  poisonous,  caustic  to  the  taste,  and  pene- 
trating odor,  similar  to  the  chloride. 

Bromide  of  Cyanogen  is  similar  to  the  preceding. 

Hydrocyanic  Acid,  .or  Prussic  Acid,  (Symb.  Cy  +  H. 
Equiv.  2 6.39 -(-1=27.39,)  was  discovered  by  Scheele,  in 
1782.  Berthollet  afterwards  ascertained  that  it  was  a  com- 
pound of  carbon,  nitrogen,  and  hydrogen ;  but  it  was  first 
procured  in  a  pure  state  by  Gay  Lussac. 

Process.  The  best  process  is  that  of  Vauquelin.  Fill  a 
narrow  tube,  placed  horizontally,  with  fragments  of  bicyan- 
uret  of  mercury,  and  then  pass  a  current  of  dry  hydrosul- 
phuric  acid  gas  very  slowly  through  it.  Double  decomposi- 
tion ensues  as  soon  as  the  gas  comes  in  contact  with  the 
bicyanuret,  when  hydrocyanic  acid  and  bisulphate  of  mercury 
are  formed.  When  the  bicyanuret  becomes  black,  the  acid 
is  expelled  by  a  gentle  heat,  and  collected  in  a  receiver  sur- 
rounded with  ice. 

Properties.  It  is  a  limpid,  colorless  liquid,  of  a  strong, 
but  agreeable  odor,  similar  to  that  of  peach  blossoms.  It 
excites,  at  first,  a  sensation  of  coolness  on  the  tongue,  which 
is  soon  followed  by  heat;  but,  when  diluted,  it  has  the  flavor 
of  bitter  almonds;  exceedingly  volatile;  boils  at  79°,  and 


190  Sulphur. 

congeals  at  zero',  unites  with  alcohol  and  water  in  all 
proportions,  but  possesses  very  feeble  acid  properties. 

It  is  a  most  virulent  poison.  A  single  drop,  if  placed  on 
the  tongue  of  a  dog,  causes  instant  death.  A  girl  swallowed 
a  small  quantity  of  it  diluted  with  alcohol,  and  fell  instantlv, 
as  if  struck  with  lightning,  and  died  in  two  minutes. 

A  professor  of  Vienna  put  drops  upon  his  arm,  and  was 
deprived  of  life  in  a  few  minutes.  But  though  a  most  potent 
poison  in  its  pure  state,  when  much  diluted,  it  has  been  em- 
ployed as  a  medicine,  in  cases  of  consumption,  with  beneficial 
effects.  This,  like  many  other  violent  poisons,  cannot  be 
employed  for  criminal  purposes,  without  the  almost  certain 
risk  of  being  discovered.  It  Exists  in  the  laurel,  peach,  and 
in  beef-steak. 

SECT.  9.     SULPHUR. 


Sulphur  has  been  known  from  the  remotest  antiquity. 

Natural  History.  It  exists  in  nature,  in  a  pure  state,  in 
the  vicinity  of  volcanoes.  It  collects  in  the  craters,  either  in 
fine  powder  or  in  crystalline  solids;  but  it  exists  more  abun- 
dantly in  combination  with  the  metals,  forming  the  sulphurets 
of  iron,  copper,  lead,  silver,  etc.,  from  which  it  may  be  sub- 
limed by  heat,  but  is  not  quite  pure.  It  is  found  also  in  many 
mineral  waters  ;  in  many  minerals,  such  as  gypsum,  sulphate 
of  strontia,  etc.;  in  all  animals,  and  some  plants. 

Process.  The  sulphur  of  commerce  exists  in  two  states  ; 
in  rolls,  called  roll  brim  ft  our  t  and  in  fine  powder,  called  flow- 
ers of  fiilp  hur  ;  but  the  two  varieties  are  readily  resolved  into 
each  other  by  the  application  of  heat. 

Exp.  Heat  a  brick,  or  small  iron  cup,  to  nearly  a  red  heat.  Place 
upon  it  roll  brimstone,  and  invert  over  it  a  bell-glass  receiver  ;  the 
sulphur  will  sublime*  i.e.,  pass  into  a  fine  po\ydt-r,  like  vapor,  and  col- 

*  This  may  serve  to  illustrate  the  process  of  svUim&tion  as  applied 
to  other  substances.  Camphor  and  gum  benzoin  are  easily  sublimed. 
The  process  of  converting  mercury  into  vapor,  and  condensing  it,  is 
also  called  sublimation,  .although  it  is  a  liquid. 


Sulphur.  —  Properties.  191 

lect  on  the  sides  of  the  vessel.     In  this  way  the  flowers  of  sulphur  are 
prepared. 

Properties.  Sulphur  is  a  brittle  solid,  of  a  lemon-yellow 
color,  nearly  tasteless,  and  inodorous,  except  when  rubbed  or 
heated.  It  is  a  non-conductor  of  electricity,  but  becomes  neg- 
atively electrified  by  friction  ;  fuses  at  216°  Fahr. ;  possesses 
the  highest  degree  of  fluidity  between  230°  and  280°,  and  is 
of  an  amber  color;  at  320°,  it  begins  to  thicken,  acquiring  a 
red  tint ;  between  423°  and  4S2°,  it  is  so  tenacious  as  to  re- 
main in  the  vessel  when  inverted ;  but,  from  482°  to  its  boiling 
point,  it  grows  fluid  again,  and  sublimes  rapidly  from  550°  to 
630°  Fahr. 

When  cooled  from  the  several  temperatures  above  named,  it 
possesses  different  dtgrees  of  consistency.  Cooled  suddenly 
from  the  most  fluid  state,  it  is  hard  and  brittle;  but  if  plunged 
into  cold  water  between  the  temperatures  of  320°  and  482°, 
it  is  soft,  and  may  be  drawn  out  like  wax;  cooled  from  the 
boiling  point,  it  is  of  a  deep  red-brown  color,  very  soft  and 
transparent.  It  is  prepared  in  this  way  for  taking  seals. 
The  native  crystals  are  octohedrons,  with  rhombic  bases; 
those  formed  artificially  occur  in  oblique  rhombic  prisms. 

Exp.  Melt  a  few  pounds  of  sulphur  in  an 
earthrii  crucible,*  (Fig.  63,)  and,  when  it  is 
partially  cooled,  pierce  the  crust  so  thai  the 
fluid  parts  may  flow  out;  on  breaking  the 
mass  when  cooled,  the  interior  will'exhibit  a 
cluster  of  beautiful  crystals.  Fig.  81  rep- 
resents a  section  of  the  crucible  containing 
the  sulphur  after  it  has  cooled. 

Sulphur  is  soluble  in  boiling  oil  of 
turpentine,  which  is  a  test  of  its  puri- 
ty. Sulphur  is  highly  combustible ;  it 
burns  with  a  pale  blue  flame,  and  com- 
bines readily  with  the  metals. 

Exp.  Mix  copper  or  iron  filings  with  sulphur,  and  heat  them  in  a 
glass  tube,  or  crucible,  by  a  spirit  lamp.  The  sulphur  will  combine, 
and  form  sulphurets  of  these  metals. 

Impurities.     Sulphur  contains  some  hydrogen  in  its  purest 

*  There  are  four  principal  varieties  of  crucibles  :  — 1.  Wedgwood  cru- 
cibles are  made  of  a  mixture  of  burned  and  unburned  clay ;  2.  Black 


192  Sulphur.  —  Sulphurous  Acid. 

state;    but  the  more   common    ingredients  are  earthy   sub- 
stances and  arsenic  ;   the  latter  is  tested  by  ammonia. 

Uses.  Employed  extensively  in  the  manufacture  of  gun- 
powder, for  seals,  medallions,  and  as  a  cement  for  iron. 
Used  in  medicine,  for  the  diseases  of  the  skin,  humors,  etc. 
The  milk  of  sulphur,  which  is  sulphur  combined  with  water, 
and  precipitated  from  some  of  its  alkaline  solutions  by  an 
acid,  occurs  in  a  gray  powder,  and  is  sometimes  used  in 
medicine. 

Hyposulplmrous  Acid.  Symb.  2S  +  2O.  Eq.  32.2+ 16= 
48.2.  It  is  difficult  to  procure  this  in  a  pure  state.  It  may 
be  formed  by  digesting  sulphur  in  a  solution  of  any  sulphitr. 
It  is  distinguished  by  uniting  with  the  oxide  of  silver,  which 
separates  the  acid  from  soda. 

Sulphurous  Acid.  Symb.  S  +  2O  or  SO8.  Eq.  16.1  -f 
16  =  32.1.  Sp.  gr.  2.2117,  air=l. 

History.  Sulphurous  acid  appears  to  have  been  known 
from  an  early  period.  Stahl  first  pointed  it  out  as  a  distinct 
substance;  but  its  discovery  in  a  pure  state  was  made  by 
Priestley,  in  1774,  and  accurately  analyzed  since,  by  Gay 
Lussac  and  Berzelius.  It  exists  in  nature  in  the  vicinity  of 
volcanoes,  and  issues  from  the  fissures  in  the  craters,  and 
from  the  lava,  often  in  immense  quantities. 

Process.  Burn  sulphur 'in  common  ;iir,  or  in  dry  oxygen 
gas,  over  mercury;  but  the  best  method  is  to  put  2  parts 
of  mercury  and  3  of  sulphuric  acid  into  a  retort,  and 
apply  the  heat  of  a  lamp,  and  collect  over  mercury.  . 

Theory.  The  sulphuric  acid  has  3  equiv.  of  oxygon,  one  of  which 
unites  with  the  mercury,  forming  the  oxide  of  mercury,  which  com- 
bines with  some  undecomposed  sulphuric  acid,  and  forms  the  sul- 

Icad  crucibles  are  formed  by  a  mixture  Fig.  84 

of  clay  and  plumbago ;  3.  Hessian 
crucibles  are  composed  of  a  mixture 
of  sand  and  clay  ;  4.  Metallic  cruel- 
lies  are  made  of  silver,  platina,  &c. 
These  latter  are  used  with  the  spirit 
lamp  in  analytical  processes.  The 
form  of  these  vessels  is  represented 
in  Fig.  84.  Metallic  and  porcelain 
crucibles  are  generally  provided  with 
covers  and  stands,  as  in  the  figure, 
but  the  best  stand  is  a  piece  of  fire- 
brick. 


Sulphurous  Acid.  193 

phate  of  mercury,  which  remains  in  the  retort,  and  the  sulphurous  acid 
comes  over  in  the  gaseous  state.  The  gas  is  heavier  than  the  air,  and 
can  be  collected  in  a  manner  described  on  page  139,  fig.  64. 

Properties.  A  transparent,  colorless  gas,  sour  to  the 
taste,  and  pungent,  suffocating  odor,  by  which  it  is  distin- 
guished from  all  other  gases ;  extinguishes  burning  bodies, 
but  is  not  combustible. 

Exp.  A  candle  immersed  in  a  jar  of  this  gas  is  instantly  extin- 
guished. 

It  is  irrcspirable,  and  fatal  to  animal  life.  When  largely 
diluted  with  air,  it  excites  coughing,  and  uneasiness  about 
the  chest ;  when  perfectly  pure,  it  excites  spasms  of  the  glot- 
tis, which  prevent  its  introduction  into  the  lungs  ;  of  course, 
an  animal  confined  in  it  is  instantly  suffocated. 

It  reddens  vegetable  colors,  and  then  discharges  them. 

Exp.  Place  a  rose  over  an  ignited  sulphur  match  in  the  open  air, 
and  it  will  turn  white  ;  hence  it  is  used  for  bleaching  straw,  silk,  arid 
for  removing  fruit-stains  from  woollen  cloths,  etc. 

It  has  a  strong  attraction  for  water  and  oxygen.  Water 
absorbs  it  so  rapidly,  that,  if  ajar  of  the  gas  be  inverted  over 
it,  the  atmosphere  will  force  the  water  into  the  jar  with  great 
violence  ;  recently-boiled  water  absorbs  33  times  its  volume. 

Sulphurous  acid  will  remain  with  dry  oxygen  without 
change,  but  if  water  be  present,  it  combines  with  oxygen, 
and  forms  sulphuric  acid.  It  instantly  decomposes  those 
oxides,  the  metals  of  which  have  a  weak  affinity  for  oxygen, 
such  as  those  of  gold,  platinum,  and  mercury.  Nitric  acid 
yields  to  it  one  proportion  of  oxygen,  and  converts  it  to  sul- 
phuric acid. 

Liquid  Sulphurous  Acid.  It  becomes  liquid  by  the  pres- 
sure of  two  atmospheres,  and  even  by  surrounding  it  with  a 
freezing  mixture.  In  this  state  it  is  anhydrous,  a  little 
heavier  than  water,  (sp.  gr.  1.45,)  and  boils  at  14°  Fahr. 

By  its  evaporation,  it  produces  so  intense  a  degree  of 
cold,  that  mercury  may  be  frozen,  and  several  of  the  gases 
rendered  liquid. 

Exp.     Pour  liquid  sulphurous  acid  upon  water  contained  in  a  shal- 
17 


194  Sulphur. 

low  vessel ;  the  acid  will  boil,  and  its  vapor  will  absorb  so  much 
caloric  that  the  water  will  soon  be  frozen. 

Exp.  Or  pour  it  upon  mercury  in  a  shallow  dish,  and  place  it  under 
the  exhausted  receiver  of  an  air-pump ;  the  mercury  itself  will  soon 
congeal. 

It  may  be  obtained  in  the  solid  form  in  crystals  containing 
water,  by  passing  the  moist  gas  through  a  receiver,  cooled 
from  50°  to  14°  Fahr. 

Uses.  Sulphurous  acid  is  often  employed  for  bleaching 
purposes,  for  whitening  straw  and  silks,  and  for  the  barbarous 
purpose  of  killing  bees. 

Ilyposulphuric  Acid.  Symb.  2S  -f-  5O.  Equiv.  32.2  -f-  40 
=  72.2.  This  acid  was  discovered  in  1819,  by  Welter  and 
Gay  Lussac. 

Process.  It  may  be  formed  by  passing  sulphurous  arid 
gas  through  water  containing  peroxide  of  m  By 

the  interchange  of  elements,  th:1  sulphate  of  the  peroxide  and 
the  hyposulphate  of  the  protoxide  of  manganese  are  formal ; 
the  latter  remains  in  solution.  The  manganese  is  thrown 
down  by  pure  baryta,  and  the  hyposulphate  of  baryta  ob- 
tained, which  crystallizes  by  evaporation,  and  is  then  decom- 
posed by  sulphuric  acid,  by  which  the  sulphate  of  baryta  is 
precipitated,  and  hyposulphuric  acid  remains  in  solution. 

Properties.  Colorless,  inodorous,  sour  to  the  taste,  red- 
dens litmus,  and  cannot  be  wholly  freed  from  water. 

Sulphuric  Acid.  Symb.  S  +  3O,  SO3,  or  S.  Equiv.  HI. I 
-f-24  =  40.1.  Sulphuric  acid  was  discovered  by  Basil 
Valentine,  near  the  close  of  the  fifteenth  century.  It  is 
commonly  called  oil  of  vitriol,  because  it  was  first  obtained 
by  the  distillation  of  green  vitriol,  (sulphate  of  iron  or  cop- 
peras.) It  exists  in  nature  abundantly  in  the  sulphate  of  lime, 
(gypsum.) 

Process.  Anhydrous  sulphuric  acid  may  be  obtained  from 
the  hydrous  acid,  manufactured  at  Nordhausen,  in  Germany, 
from  the  protosulphate  of  iron,  and  called  fuming  sulphuric, 
acid.  But  the  best  method  is  that  of  Professor  Mosander,  of 
Stockholm.  —  Saturate  the  oxide  of  antimony  with  excess  of 
sulphuric  acid,  and  then,  by  a  slow  heat,  drive  off  the  excess 


Sulphurous  Acid.  195 

of  acid,  when  the  salt  will  crystallize  as  a  dry  sulphate  of 
antimony.  Expose  this  salt  to  a  dull  red  heat  in  a  retort,  and 
the  anhydrous  acid  will  be  driven  off,  and  may  be  collected 
in  a  dry  receiver,  surrounded  with  ice. 

Properties.  In  this  state,  the  acid  has  some  peculiar  prop- 
erties. It  is  a  white,  opaque  solid  ;  fuses  at  66°  Fahr. ;  sp.  gr. 
1.99;  boils  between  104°  and  122°,  forming  a  transparent 
vapor  ;  has  a  powerful  affinity  for  water,  so  that,  on  exposing 
it  to  the  air,  it  flies  off  in  white  fumes. 

Hydrous  Sulphuric  Acid,  which  is  the  ordinary  acid  of 
commerce,  may  be  obtained  by  several  modes. 

Exp.  Burn  a  mixture  of  8  parts  of  sulphur  to  1  of  nitre  in  a  vessel 
of  oxygen  gas  containing  a  vegetable  infusion;  the  acid  will  be  ab- 
sorbed by  the  water,  and  change  the  infusion  red. 

But  the  process  for  manufacturing  this  acid  in  the  arts,  is 
done  in  chambers  lined  with  sheet  lead*  8  parts  of  sul- 
phur to  1  of  nitre,  coarsely  bruised  and  mixed  together, 
are  put  upon  iron  plates,  1  Ib.  to  300  cubic  feet  of  air.  The 
mixture  is  ignited  by  a  hot  iron,  and  the  door  closed.  Water, 
to  the  depth  of  6  inches,  covers  the  floor,  and  absorbs  the 
acid  as  fast  as  formed.  The  room  is  then  ventilated,  and  the 
process  repeated  every  four  hours,  until  the  water  is  suffi- 
ciently acid  ;  or,  by  an  improvement  in  the  structure  of  the 
room,  the  sulphur  is  burned  in  a  separate  room,  and  the  air, 
admitted  continually,  carries  the  acid  vapor  into  the  chamber, 
where  it  is  condensed  by  the  water.  This  acidulated  water 
is  then  drawn  off  and  concentrated  by  heat,  in  leaden  boilers, 
until  it  is  of  the  specific  gravity '1.450,  and  the  concentration 
is  finished  in  glass  or  platinum  dishes  placed  in  sand  baths. 

Theory.  By  the  combustion  two  gases  are  formed  —  sulphurous  acid 
from  the  sulphur,  and  binoxide  of  nitrogen  from  the  nitre.  The  latter 
combines  with  the  oxygen  of  the  air,  and  is  converted  into  the  nitrous 
acid.  The  sulphurous  and  nitrous  acids  then  combine  with  the  watery 
vapor,  and  form  a  crystalline  solid,  composed  of  sulphuric  acid,  hyponi- 
trous  acid,  and  water.  When  this  solid  drops  into  the  water,  it  is 
instantly  decomposed,  the  sulphuric  acid  is  retained  in  the  water,  and 
nitrous  acid  and  binoxide  of  nitrogen  escape.  The  nitrous  acid  thus 
set  free,  as  well  as  that  formed  by  the  binoxide  and  oxygen  of  the  air, 
again  combines  with  the  moist  sulphurous  acid,  and  forms  the  solid, 
vhich  sinks  to  the  water,  and  is  decomposed  again.  This  process  con- 

*  The  usual  size  of  the  chamber  is  20  feet  long,  and  12  wide ;  but 
in  one  establishment  in  England,  the  chamber  is  iJiO  feet  by  40/ and  20 
high,  containing  96,000  cubic  feet. 


196  Sulphur. 

tinues,  until  the  whole  is  converted  into  sulphuric  acid,  and  absorbed 
by  the  water. 

Properties.  Hydrous  sulphuric  acid,  when  pure,  is  an 
oily,  limpid  liquid,  colorless,  inodorous,  intensely  sour  and 
corrosive ;  destroys,  by  the  aid  of  heat,  all  animal  and  vege- 
table bodies,  with  the  deposition  of  charcoal,  and  formation 
of  water ;  hence  the  acid  often  attains  a  brown  tinge  by 
charring  substances  which  accidentally  fall  into  it ;  boils  at 
620°  Fahr.,  and  freezes  at  -15°.  When  its  specific  gravity  is 
1.78,  it  congeals  above  32°,  and  remains  solid  up  to  45°; 
but  when  mixed  with  twice  its  weight  of  water,  it  congeals 
at  -36°. 

It  has  a  powerful  affinity  for  water.  It  combines  with 
the  water  of  the  air,  even  at  boiling  temperatures,  so  power- 
fully that  its  greatest  concentration  can  be  effected  only  by 
glass  or  platinum  retorts  with  narrow  mouths. 

Exp.  4  parts  of  sulphuric  acid  and  1  of  water,  each  at  50°,  when 
poured  together,  have  a  temperature  of  300°.  The  heat  is  occasioned 
by  the  diminution  of  bulk,  by  which  the  insensible  caloric  becomes  free. 

Exp.  2  parts  of  acid  and  3  of  snow  form  a  mixture  which  will 
freeze  water,  and  the  thermometer  will  sink  even  to  -23°.  The  cold 
results  from  its  affinity  for  water  ;  it  dissolves  the  snow  to  obtain  it ; 
and  the  heat  necessary  to  render  the  water  liquid  is  absorbed  from  the 
acid  and  the  snow,  and  passes  into  an  insensible  state. 

Exp.  \  part  of  snow  to  3  of  acid  will  produce  a  heating  mixture, 
because  the  condensation  develops  more  heat  than  is  required  to  HH  It 
the  snow. 

The  decomposition  of  sulphuric  acid  is  effected  by  heat, 
and  by  the  non-metallic,  combustibles. 

Exp.  Pass  hydrogen  gas  and  sulphuric  acid  through  a  red-hot  por 
celaiu  tube. 

Exp.  Heat  this  acid  with  charcoal,  or  put  into  it  vegetable  sub- 
stances. 

Exp.  Expose  the  acid  to  the  galvanic  battery;  the  sulphur  will 
appear  at  the  negative,  and  tho  oxygen  at  the  positive  pole.  Its  spe- 
cific gravity  never  exceeds  1.850. 

Its  strength  is  tested  by  its  specific  gravity,  and  by  the 
quantity  required  to  saturate  a  given  portion  of  an  alkali. 
100  grains  of  the  carbonate  of  soda  will  neutralize  9*2  of 
pure  sulphuric  acid.  It  may  be  detected  in  any  solution  by 
the  chloride  of  barium,  by  which  a  white,  insoluble  solid  is 
precipitated  —  the  sulphate  of  baryta. 


Sulphur  and  Hydrogen.  .  197 

It  is  one  of  the  most  powerful  of  acids,  reddens  the  vege- 
table infusions,  unites  with  bases,  and  forms  salts,  which  are 
called  sulphates. 

It  is  a  most  violent  poison.  The  best  antidote  is  dry  mag- 
nesia. If  water  be  taken,  it  will  produce  a  very  great  heat, 
and  thus  increase  its  injurious  effects. 

Uses.-  It  is  one  of  the  principal  acids  of  chemistry  and 
of  the  arts,  in  which  greater  quantities  are  employed  than 
of  any  other  acid ;  for  the  formation  of  most  of  the  other 
acids  ;  for  the  preparation  of  soda  from  salt,  of  alurn  from 
.sulphate  of  iron  ;  for  obtaining  chlorine  and  other  gases  ;  for 
dissolving  indigo  for  dyes.  It  is  used  in  medicine  as  a  tonic. 

Dichlori.de  of  Sulphur  (Symb.  2S-J-C1.  Eq.  67.62.  Sp.  gr.  1.687) 
was  discovered  by  Dr.  Thompson,  in  Ib04.  Prepared  by  passing  a 
current  of  chlorine  gas  over  flowers  of  sulphur,  gently  heated,  till 
nearly  all  the  sulphur  disappears.  The  dichloride  is  then  obtained  by 
distillation  in  the  form  of  a  reddish  liquid. 

Iodide  of  Sulphur.  Firs*  described  by  Gay  Lussac.  Formed  by 
heating  4  parts  of  iodine  with  1  of  sulphur.  A  dark-colored  substance, 
easily  decomposed  by  heat. 

Bromide  of  Sulphur  is  obtained  by  pouring  bromine  on  sublimed 
sulphur.  The  product  is  an  oily  liquid,  of  a  reddish  tint;  odor  resem- 
bles the  dichloride  of  sulphur. 

I 

Sulphur  and  Hydrogen. 

Hydrosulphuric  Acid.  Symb.  SH.  Equiv.  16.1  +  1  = 
17.1.  Equiv.  vol.  100.  Sp.  gr.  1.1782,  air  =  l.  This  sub- 
stance was  discovered  by  Scheele,  in  1777,  and  has  been 
variously  named,  sulphureted  hydrogen  and  hydrotliionic 
acid. 

Process.  It  may  be  obtained  from  the  sulphurets  of  the 
metals.  The  one  generally  employed  is  the  protosulphurct 
of  iron,  which  is  a  native  product,  but  can  be  prepared  by 
heating  2  parts  of  iron  filings  with  1£  of  sulphur  to  a  red 
heat,  in  a  covered  crucible ;  upon  this,  in  a  retort,  pour  dilute 
sulphuric  acid,  apply  gentle  heat,  and  collect  over  water. 
Sesquisulpkuret  vf  antimony,  treated  in  the  same  manner 
with  hydrochloric  acid,  will  yield  a  purer  gas ;  the  former 
contains  a  little  iron  and  hydrogen. 

Theory.  The  oxygen  of  the  water  unites  with  the  iron,  and  its 
hydrogen  with  the  sulphur,  and  the  sulphuric  acid  unites  with  the 
oxide  of  iron ;  the  products  are  hydrosulphuric  acid  and  sulphate  of 

17* 


198  Sulphur  and  Hydrogen. 

the  protoxide  of  iron.     FeS,  SO3  and  HO  are  converted  into  SO3  -f 
FeO,  and  SH. 

Properties.  It  is  a  colorless  gas,  but  has  an  excess! a  /// 
offensive  taste  and  odor ;  it  is  this  gas  which  gives  the  odor 
to  putrescent  eggs,  sewers,  and  the  waters  of  sulphurous 
springs.  It  extinguishes  burning  bodies,  but  burns  with  a 
pale  blue  flame ;  forms  an  explosive  mixture  with  oxygen, 
and  is  so  destructive  to  animal  life  that  y-^  v  part  of  this  gas 
in  air  destroys  small  birds ;  ^  part  killed  a  middle-sized 
dog,  and  ,j-£a  part  a  horse.  If  placed  on  the  cutaneous 
surface  of  animals,  it  will  prove  fatal  to  them.  Reddens  lit- 
mus feebly,  but  unites  with  bases  and  forms  salts. 

Water  absorbs  3  volumes  of  the  gas,  and  forms  a  colorless 
liquid,  similar  to  the  gas  in  taste  and  odor.  This  water  is  a 
test  of  the.  metals.  Nitric  acid  will  cause  a  precipitate  of 
sulphur  ;  and  if  poured  into  a  bottle  of  the  gas,  a  blue  flame 
will  pervade  the  vessel,  and  sulphur  and  nitrous  acid  fumes 
be  produced.  If  exposed  to  the  air,  it  deposits,  its  sulphur 
on  the  surface  of  the  vessel ;  but  it  is  readily  decomposed  by 
metals  in  solution  ;  the  sulphur  combines  with  the  metal,  and 
the  hydrogen  is  liberated. 

It  is  also  decomposed  by  chlorine  and  iodine,  because  of 
their  great  affinity  for  hydrogen.  Hence  chloride  of  lime  is 
used  to  purify  places  rendered  noxious  by  this  gas.  It  is 
partially  decomposed  by  heat,  in  a  porcelain  tube. 

Liquid  Hydrosulphurir,  Add.  Mr.  Faraday  succeeded  in  condensing 
the  gas.  Under  a  pressure  of  17  atmospheres,  it  is  colorless,  limpid, 
and  excessively  fluid  ;  compared  with  it,  ether  appears  tenacious  and 
oily.  On  breaking  a  tube  under  water,  it  rushed  out  violently,  and 
assumed  the  gaseous  state. 

Test.  The  best  test  of  this  gas  is  carbonate  of  lead.  1 
part  of  the  gas  mixed  with  20,000  of  air  will  give  a  brown 
stain  to  a  surface  whitened  with  the  lead.  Hence  persons 
who  use  preparations  of  lead  to  improve  their  beauty,  on 
coming  into  the  vicinity  of  this  gas,  often  change  their  color. 

Exp.  Write  on  paper  with  any  of  the  salts  of  lead  in  solution,  and 
pass  a  stream  of  the  gas  over  it;  the  writing  will  instantly  appear. 

Uses.  In  medicine  for  cutaneous  eruptions,  in  the  labora- 
tory as  a  test  of  metals ;  hence  its  use  in  analytical  processes. 


Sulphur  and  Carbon. 


199 


Production  of  Sulphur  in  Volcanoes  by  the  Meeting  of  Sul- 
phurous and  Hydrosulphuric  Acids.  These  acids  are  gener- 
ated in  volcanoes,  and,  as  they  meet,  are  decomposed,  and 
sulphur  is  deposited.  This  may  be  shown  in  the  following 
manner :  — 

Let  two  small  retorts 
a,  a,  (Fig.  85,)  pass  into 
a  globe  receiver,  6,  so 
that  their  mouths  shall 
nearly  touch  each  other. 
Put  the  materials  for  sul- 
phurous acid  into  one, 
and  for  hydrosulphuric 
acid  in  the  other,  and 
apply  heat;  as  the  two 

gases  meet  in  the  receiver,  they  will  be  decomposed,  and  the 
sulphur  will  be  deposited  upon  the  interior  surface,  in  fine 
powder. 

Ht/drosulphurous  Add.  Symb.  2S  -|-  H.  Equiv.  33.2.  Discovered 
by  Schcele,  who  called  it  su/>er.*ufphureled  hydrogen.  The  names 
Injdrotluunous  acid,  per  or  bisnlphureted  hydrogen,  and  persulphuret  of 
hydrofeHfh&VG  also  been  applied  to  it. 

It  is  similar  in  taste   and    odor  to  hydrosulphuric  acid,  but  not  so 
powerful ;  semi-fluid,  inflammable,  and  easily  decomposed  by  heat  into 
sulphur  and  hydrosulphuric  acid. 
.r','--" 

Sulphur  and  Carbon. 

Bisulphurct  of  Carbon,  or  Alcohol  of  Sulphur,  Carbosul- 
phuric  Acid.  Discovered  accidentally  by  Professor  Lampa- 
dius,  in  177G ;  but  its  true  nature  w^is  first  pointed  out  by 
Clement  and  Desormes. 

Process.  It  is  obtained  by  heating,  in  a  close  vessel,  the  native 
bisulphuret  of  iron  (iron  pyrites}  with  one  fifth  of  its  weight  of  dry 
charcoal.  "  The  compound,  as  it  is  formed,  should  be  conducted,  by 
means  of  a  glass  tube,  into  a  vessel  of  cold  water,  at  the  bottom  of  which 
it  is  collected.  To  free  it  from  moisture  and  adhering  sulphur,  it  should 
be  distilled  at  a  low  temperature,  in  contact  with  chloride  of  calci- 
um."—T. 

Properties.  A  transparent,  colorless  liquid,  remarkable 
for  its  high  refractive  power,  acid,  pungent,  and  somewhat 
aromatic  taste,  and  fetid  odor;  specific  gravity,  1.272,  ex- 
ceedingly volatile;  boils  at  110°;  very  inflammable,,  and 
burns  with  a  pale  blue  flame.  With  oxygen,  its  vapor  forms 
an  explosive  mixture ;  with  binoxide  of  nitrogen,  it  forms  a 


200  Cyanogen  and  Sulphur. 

mixture  which  burns  with  dazzling  brilliancy ;  dissolves  in 
alcohol  and  ether,  and  is  precipitated  by  water;  dissolves 
phosphorus,  sulphur,  and  iodine,  giving  to  a  solution  of  the 
latter  a  beautiful  pink  color.  It  is  decomposed  by  chlorine. 

Cyanogen  and  Sulphur. 

Sulphurtt  of  Cyanogen  was  discovered  in  1828,  by  M.  Lassaigne,  by 
the  action  of  bit- van u ret  of  mercury,  in  fine  powder,  upon  half  its 
weight  of  bichloride  of  sulphur,  confined  in  a  small  glass  globe,  and 
exposed  for  two  or  three  weeks  to  daylight.  A  small  quantity  of  rrvs- 
tals,  biting  to  the  tongue,  and  of  a  penetrating  odor,  collected  in  the  up- 
per part  of  the  vessel,  which  form  red-colored  compounds  with  per 
salts  of  iron. 

Bimdpkurtt  of  Cyanogen  (Sy  mb.  2S  -f  Cy)  was  discovered  by  Liebig, 
by  exposing  fused  sulphocyanuret  of  potassium  to  a  current  of  dry  chlo- 
rine gas ;  it  forms  a  dry,  yellow  powder. 

Hydrosulphocyanic  Jcid.  Syrab.  S*CyH.  Equiv.  50.59.  Dis- 
covered in  1808,  by  Mr.  Porritt,  who  ascertained  it  to  be  a  comp«>nn<l 
of  sulphur,  carbon,  hydrogen,  and  nitrogen.  It  is  sometimes  called 
sulphoryunic  acid,  and  may  be  formed  by  suspending  aulphocyanun  t 
of  silver  or  mercury  in  water,  and  by  transmitting  through  it  a  current 
of  hydrosulphuric  acid  gas;  sulphuret  of  silver  or  mercury,  and  hydro- 
sulphocyanic  acid,  are  generated;  filter  the  solution,  and  expel  the 
excess  of  gas  by  heat. 

Properties.     A  liquid,  either  colorless,  or  a  shade  of  pink  ; 
odor  resembling  vinegar ;  sp.  gr.  1.002 ;  boils  at  216.5° ;  • 
tallizes  in  six-sided  prisms  at  45.5°  Fahr. ;  acid  to  the  t 
and  by  the  chemical  tests.     It  also  unites  with  alk  ilifs. 

Test  of  its  Presence.  A  salt  of  the  peroxide  of  iron,  to 
which  it  gives  a  deep  blood-red  solution;  decomposed  by 
exposure  to  the  air,  and  by  chloric  or  nitric  acid. 

Cyanohydrosulphuric  Acid  (Symb.  S'Cyll*.  Equiv. 
60.59)  may  be  obtained  by  passing  a  current  of  hydrosul- 
phuric acid  through  a  saturated  solution  of  cyanogen  in  alco- 
hol. The  liquid  acquires  a  reddish-brown  tint,  and  numer- 
ous small  crystals,  of  an  orange-red  color,  are  generated.  It 
is  considered  by  Liebig  to  be  similar  in  composition  to  the 
preceding,  but  to  have  one  equivalent  more  of  hydrogen. 


SECT.  10.     PHOSPHORUS. 


Symb.  P.      Equi,      f  7       Sp.  g,  »  =    . 


History.     Phosphorus  received  its  name  from  the  property 
of  shining  in  the  dark.* 

*  <f>w$,  light,  and  <fiqnvt  to  carry. 


Phosphorus.  201 

It  was  discov  T<  1  by  Fran  It,  an  alchemist  of  Hamburg,  in 
1609.  It  was  formerly  obtained  from  urine,  but  the  process 
of  obtaining  it  was  for  a  long  time  kept  secret,  and  small 
quantities  only  were  procured.  Scheele  obtained  it  from 
bones,  and  invented  the  method  now  generally  employed.  It 
exists  in  the  boiies  of  all  animals,  in  the  state  of  phosphate 
of  lime.  A  middle-sized  man  has  about  one  pound  of  phos- 
phorus in  his  bones. 

Process.  The  bones  are  calcined  in  an  open  fire,  reduced 
to  a  fine  powder,  and  digested  for  .a  few  days  with  one  half 
their  weight  of  sulphuric  acid,  with  sufficient  water  to  give 
them  the  consistency  of  paste.  The  phosphate  of  lime  is 
decomposed,  and  the  sparingly-soluble  sulphate  and  soluble 
superphosphate  of  lime  are  generated.  The  latter  is  then 
dissolved  in  warm  water,  filtered  and  evaporated  to  the  co% 
sist$ncy  of  sirup. 

It  is  then  mixed  with  J  part  of  charcoal,  in  an  earthen  re-_ 
tort  lined  with  clay,  heated  in  a  furnace  to  a  high  temper?- 
ture,  when  the  vapor  of  the  phosphorus  comes  over,  and  is 
conducted  by  a  tube  into  a  bowl  of  water,  where  it  is  con- 
densed into  a  reddish-brown  solid.  This  is  then  fused  in  hot 
water,  and  distilled  in  hydrogen,  or  passed  through  chamois 
leather. 

Properties.  When  pure,  it  is  transparent  and  nearly  col- 
orless, or  of  a  wax  color ;  easily  cut  with  a  knife,  and  the  sur- 
face has  a  waxy  appearance  and  texture ;  fuses  at  108°,  and 
at  550°  is  converted  into  vapor ;  soluble  by  the  aid  of  heat  in 
naphtha,  in  fixed  and  volatile  oils,  and  in  the  chloride  of  sul- 
phur, sulphuret  of  carbon,  and  sulphuret  of  phosphorus.  On 
cooling  a  solution  of  the  latter,  it  crystallizes  in  dodeca- 
hedrons. 

It  is  very  inflammable.  At  common  temperatures,  it  com- 
bines slowly  with  the  oxygen  of  the  air,  giving  a  luminous 
appearance  in  the  dark. 

Exp.'  If  a  stick  be  placed  in  a  receiver  pf  air,  it  will  absorb  the  oxy- 
gen, and  leave  the  nitrogen. 

Exp.  If  a  stick  of  phosphorus  be  dusted  over  with  charcoal  or  resin, 
and  placed  under  the  receiver  of  an  air-pump,  it  will  inflame  on  ex- 
hausting the  air. 

Exp.  By  friction  it  instantly  ignites,  and  hence  is  employed  for 
matches. 


202  Phosphorus. 


Exp.    When  ignited  in  oxygen,  it  Fig.  86. 

burns  with  great  brilliancy,  This 
experiment  should  be  conducted 
in  a  large  globe  receiver,  (Fig. 
hC,)  filled  with  oxygen,  and  the 
phosphorus  placed  in  the  centre 
by  a  pendent  copper  spoon.  Dense 
white  fumes  of  phosphoric  acid  are 
formed  ;  these  often  mingle  with 
the  vapors  of  phosphorus  and  oxy- 
gen, which  renders  the  whole  in- 
Jit/  mmable;  and  hence  the  danger 
of  breaking  the  receiver. 

Let  a  stream  of  oxygen 
<r.ris  upon  phosphorus  in  a  fused 
state,  under  water,  and  flashes 
of  light  will  pass  up  through  the 
water. 

Exp.  Or  put  a  few  grains  of  chlorate  of  potassa  into  a  glass  of  water, 
in  which  is  apiece  of  phosphorus,  and  from  the  dropping  tube  pour 
«on  nitric  or  sulphuric  acids;  flashes  of  light  will  appear. 

Exp.  Drop  a  small  piece  into  a  glass  containing  a  small  quantity  of 
strong  nitric  acid  ;  it  will  burn  vividly,  and  often  explode  with  <rrtat  vio- 
»nee.  (See  Fig.  77.) 

Erp.  Sweet  oil  dissolves  iUby  the  aid  of  heat,  and  the  phosphorized 
oil  can  be  put  on  the  face  and  hair  so  as  to  render  it  luminous  in 
the  dark. 

Theory.  In  all  these  cases,  the  light  results  from  the  union 
of  phosphorus  with  oxygen  ;  so  strong  is  its  affinity  for  oxy- 
gen, that  it  should  always  be  kept  under  water.  If  exposed 
to  the  air,  and  held  in  the  hands  in  a  dry  state,  there  is  dan- 
ger of  its  entering  into  a  state  of  combustion,  especially  if 
any  friction  is  applied  to  it. 

Relation  to  Ani.-inn's.  It  is  very  poisonous;  acts  as  an 
excitant,  and  in  large  doses  it  proves  fatal  ;  but  it  is  used 
sometimes  as  a  medicine.  It  renders  water  poisonous  in 
which  it  is  kept. 

Phosphorus  and  Oxygen. 

Oxide  of  Phosjthonis.  Symb.  3P  ^  O.  Equiv.  47.1  -}-  8  =  55.  1  .  It 
is1  obtained  by  burning  phosphorus  under  hot  water,  by  a  jet  of  oxygen 
<rns.  The  substance  which  remains  after  combustion  is  of  a  red  color, 
without  taste  or  odor;  insoluble  in  water,  alcohol,  ether,  and  oil  ;  is 
not  volatilized  at  662°  Fahr.,  but  takes  fire  at.  a  low  red  heat,  in  the  air 
and  in  chlorine  gas.  This  substance  has  been  examined  by  M.  Pelouse, 
and  found  to  be  an  oxide  of  phosphorus. 

Ifypophosphorous  Acid  (Symb.  2P-J-Q-     Equiv.  31.4-)- 


Phosphoric  Acid.  203 

t. 

8  =  39.4)  was  discovered  by  Dulong,  in  1816,  and  is  obtained 
by  the  action  of  water  upon  the  phosphuret  of  barium.  Hy- 
pophosphite  of  baryta  is  formed  soluble  in  water  ;  on  filtering 
the  solution,  and  adding  sulphuric  acid  to  precipitate  the 
baryta,  th*  hypophosphorous  acid  remains,  and  is  concentra- 
ted by  evaporation  into  a  viscid  liquid,  capable  of  crystalliza- 
tion ;  this  is  the  hydrate  of  the  acid,  and  is  a  powerful  deox- 
idizing* agent. 

Phosphorous  Acid  (Symb.  2P  +  3O.  Equiv.  31.4+24  = 
55.4)  was  discovered  by  Davy,  and  may  be  obtained  by  sub- 
liming phosphorus  through  the  bichloride  of  mercury,  in  a 
glass  tube;  a  limpid  liquid  distils  over,  which  is  a  compound 
of  phosphorus  and  chlorine.  Put  this  into  water,  and  the 
hydrogen  of  the  water  unites  with  the  chlorine,  forming  hy- 
drochloric acid,  and  the  oxygen  of  the  water  combines  with 
the  phosphorus,  forming  the  phosphorous  acid.  The  solution 
is  then  evaporated  to  the  consistency  of  sirup,  to  expel  the 
hydrochloric  acid,  and  the  phosphorous  acid  crystallizes  as 
a  hydrate.  The  anhydrous  acid  may  be  obtained  by  burning 
the  phosphorus  in  highly-rarefied  air. 

Properties.  Sour  to  the  taste,  odor  like  garlic,  and  pos- 
sesses acid  properties ;  has  a  strong  affinity  for  oxygen,  and 
is  hence  easily  converted  into  phosphoric  acid ;  precipitates 
mercury,  silver,  platinum,  and  gold,  from  their  saline  solu 
tions,  in  the  metallic  form. 

Phosphoric  Acid.  Symb.  2P  +  5O.  Eq.  31.4  +  40  = 
71.4.  Under  the  term  of  phosphoric  acid,  three  compounds 
have  formerly  been  described,  affording  a  remarkable  in- 
stance of  a  class  of  bodies,  called  isomcric,  which  are  identical 
in  composition,  but  possess  different  properties.  The  names 
given  to  the  three  compounds  are,  phosphoric,  pyrophosphoric, 
and  meta  or  paraphosphoric  acids. 

1.  The  Phosphoric  Acid  has  hitherto  been  obtained  only 
in  combination  with  water  or  an  alkaline  base. 

Process.     The  superphosphate  of  lime  is  boiled  for  a  few 


*  Bodies  are  said  to  deoxidize  when  they  abstract  oxygen  from  its 
combinations  with  other  bodies,  They  are  said  to  oxidize  when  they 
yield  oxygen  to  other  bodies. 


204  Phosphorus. 

minutes  with  excess  of  carbonate  of  ammonia,  by  which  the 
lime  is  precipitated  as  a  phosphate.  After  filtration,  the  liquid 
is  evaporated  to  dryness,  and  then  ignited  in  a  platinum 
crucible,  to  expel  the  ammonia  and  sulphuric  acid. 

Properties.  Colorless,  intensely  sour,  reddens  vegetable 
infusions  powerfully,  and  neutralizes  alkalies.  In  the  state 
of  greatest  concentration,  it  is  composed  of  three  equivalents 
of  water,  and  one  equivalent  of  acid,  and  may  be  made  to 
crystallize  in  thin  plates.  It  is  remarkable  for  uniting 
with  bases,  in  the  proportion  of  1  equivalent  of  the  acid  to 
3  of  the  base,  or  the  oxygen  of  the  base  and  the  acid  as 
3  to  5. 

2.  The   Pyrophosphoric   Acid  is    obtained    by  exposing 
concentrated  phosphoric  acid  to  a  temperature  of  145°. 

Its  properties  are  generally  similar  to  the  preceding,  but 
it  is  distinguished  from  it  by  yielding  a  snow-white  pre- 
cipitate, when  neutralized  with  ammonia,  and  mixed  v.ith 
the  nitrate  of  the  oxide  of  silver.  //  is  remarkable  for  its 
tendency  to  unite  with  2  equivalents  of  a  base  to  1  of  the 
acid.  * 

3.  Meta  or  Paraphosphoric  Acid  is  obtained  by  burniuir 
phosphorus  in  dry  air, or  oxygen  gas.     The  acid  appears  in 
small  crystals,  like  snow,  on  the  interior  of  the  vessel.     It  is 
formed,  combined  with  water,  by  heating  to  redness  the  two 
preceding    acids;    when    fused,   it  cools   into  a   brittle  and 
transparent  solid,  resembling  ice,  hence  called  glacial  phos- 
phoric acid,  very  deliquescent,  and  hence  must  be  kept   in 
close  bottles.     //  is  distinguished  from  the  others  by  uniting 
1  equivalent  of  a  base  to  1  of  the  acid. 

Phosphorus  and  Chlorine. 

The  Scsqmchloride  of  Phosphorus  (Symb.  2P  +  3C1. 
Equiv.  31.4  +  106.26=137.66.  Sp.  gr.  1.45)  may  be 
formed  by  passing  the  vapor  of  phosphorus  over  corrosive 
sublimate,  in  a  glass  tube,  or  by  heating  the  perchloride  with 
the  phosphorus. 

Properties.     It  is  a  clear,  limpid  liquid,  not  acid  by  the 


Phosphorus  and  Hydrogen.  205 

chemical  tests,  though  it  emits  acid  fumes  when  exposed  to 
the  air.  This  is  due  to  the  affinity  of  the  chlorine  for  the 
hydrogen  of  the  water  contained  in  the  air.  When  mixed 
with  water,  mutual  decomposition  takes  place,  with  evolution 
of  heat,  and  the  formation  of  hydrochloric  and  phosphoric 
acids. 

The  Perchloride  of  Phosphorus  is  formed  by  the  spon- 
taneous combustion  of  phosphorus  in  chlorine  gas.  Symb. 
2P  +  5C1.  Eq.  208.5. 

Properties.  A  white  solid,  volatile  at  a  temperature  below  212°  ; 
heated  under  pressure,  it  fuses,  and  forms,  in  cooling,  transparent, 
prismatic  crystals.  Thrown  into  water,  mutual  decomposition  ensues. 

Iodides  of  Phosphorus.  There  appear  to  be  three  com- 
pounds of  iodine  and  phosphorus,  produced  by  the  spontane- 
ous combustion  of  the  two  substances. 

The  Prutiodide  (Symb.  P+I.  Equiv.  142)  has  a  yellow  color, 
fuses  at  212°,  sublimes  by  heat  unchanged,  and  is  decomposed  by 
water. 

The  Sesquiodide  (Symb.  2P  -j-  31.  Equiv.  410.3)  is  a  dark-gray 
crystalline  mass,  fuses  at  84°. 

The  Periudide  (Symb.  2P  +  5I.  Equiv.  6G2.9)  is  a  black  com- 
pound, fusible  at  114°. 

Bromides  of  Phosphorus  are  formed  by  bringing  phospho- 
rus and  bromine  into  contact,  in  a  flask  filled  with  carbonic 
acid. 

The  Protobromide  (Symb.  P-f  Br.  Equiv.  94.1)  is  a  liquid  formed 
at  the  bottom  of  the  flask,  easily  converted  into  vapor  by  heat,  acts 
energetically  upon  water,  and  mutual  decomposition  takes  place. 

The  Perbromide  (Symb.  2P-|-5Br.  Equiv.  423.4)  is  a  yellow  solid, 
converted  by  heat  into  a  red-colored  liquid,  and  ii^to  a  vapor  of  a  simi- 
lar tint.  When  cooled  from  fusicm,  it  yields  rhombic  crystals.  Emits 
dense,  penetrating  fumes  when  exposed  to  the  air,  and  is  decomposed 
by  water  and  chlorine. 

Phosphorus  and  Hydrogen. 

Phosphuret  of  Hydrogen,  (Symb.  2P  +3H.  Equiv.  31.4 
_|_3=i34.4,)  called  also  hyduret  of  phosphorus,  was  discov- 
ered in  1812,  by  Sir  H.  Davy,  by  heating  hydrated  phospho- 
rous acid  in  a  retort. 

Properties.  It  is  colorless,  with  the  odor  of  garlic ;  does 
not  take  fire  spontaneously  in  air,  but  instantly  inflames  in 
18 


206 


Phosphorus. 


chlorine  gas,  with  a  white  light ;    forms  with  oxygen  a  det- 
onating mixture. 

Perphosphuret  of  Hydrogen  is  isomeric  with  the  prece- 
ding. It  was  discovered  in  1783,  by  Gengembre,  and  has 
been  since  examined  by  Dalton,  Thompson,  and  others.  The 
names  phosphureted  hydrogen  and  hyduret  of  phosphorus 
have  also  been  applied  to  it. 

Process.  For  the  purposes  of  experiment,  it  is  easily 
prepared  in  the  following  manner  :  Fill  a  pint  retort  half  full 
of  recently-slacked 'lime,  and  put  into  it  a  stick  of  ph<«spli<  >ru< 
two  or  three  inches  long,  cut  into  strips.  Then  pour  ^  ]\  a 
strong  solution  of  carbonate  of  potassa,  filling  the  retnrt  quite 
full.  Place  the  beak  of  the  retort  in  the  cistern,  and  apply 
heat.*  The  gas  will  soon  form  and  inflame  when  it  comes 
in  contact  with  the  air,  forming  beautiful  wreaths  of  snmkc, 
which  rise  up  from  the  water.  Or  it  may  be  collected  like 
any  other  gas. 

Properties.  This  gas  is  colorless,  and  has  a  highly-olTcn- 
sive  odor,  and  bitter  taste ;  will  neither  support  flame  nor 
respiration. 

Fig.  87. 


o 


Inflames  spontaneously  when  admitted  into  air,  and  explo- 
sively with  oxygen  gas.  As  the  bubbles  of  the  gas  (Fig.  87) 
rise  through  the  water  in  the  cistern  b  into  the  air,  they 
inflame  successively,  the  phosphoric  acid  and  vapor  form  a 
series  of  rings,  as  c,  of  dense  white  smoke,  continually 

*  The  readiest  mode  of  obtaining  this  gas  is  to  heat  phosphorus  in 
connection  with  quicklime,  forming  the  phosphuret  of  lime.  Drop 
this  into  water  acidulated  with  hydrochloric  acid.  The  water  is  de- 
composed, and  its  hydrogen  and  oxygen  unite  with  the  phosphorus, 
and  form  hypophosphorous  acid,  phosphoric  acid,  and  phosphuret  of 
hydrogen. 


Boron.  207 

increasing  in  size  as  they  arise,  and  producing  one  of  the 
most  striking  and  beautiful  appearances  in  experimental 
chemistry.  If  a  bubble  of  the  gas  is  admitted  into  a  receiver 
of  oxygen  gas,  a  bright  flash  of  light  is  seen,  and  the  receiver 
is  jarred  by  the  concussion.  This  is  one  of  the  most  re- 
markable properties  of  this  gas,  and  distinguishes  it  from  all 
other  gases.  It  is  often  produced  by  the  decomposition  of 
bones,  in  swamps  and  graveyards,  and  gives  rise  to  those 
lights  which  are  frequently  seen  about  such  places.  It  is  the 
real  "  Jack  o'  the  lantern,"  or  "  Will  o'  the  wisp." 

Water  absorbs  one  eighth  volume  of  this  gas,  and,  if  the  gas 
is  suffered  to  remain  over  water  for  a  few  days,  it  loses  its 
spontaneous  inflammability,  but  will  inflame  on  the  applica- 
tion of  a  lighted  taper. 

Phosphorus  and  Sulphur. 

Sulphurct  of  Phosphorus.  The  nature  of  this  compound  is 
not  accurately  settled  ;  it  is  formed  by  bringing  sulphur  in 
contact  with  fused  phosphorus.  They  act  on  each  other 
with  great  violence,  producing  a  compound  of  a  reddish- 
brown  color,  which  fuses  at  16°  Fahr.,  and  is  highly  combus- 
tible. 

SECT.  11.     BORON. 
Symb.  B.     Eq.  10.9.     Equiv.  vol.  100. 

This  substance  was  discovered  in  1807,  by  Sir  H.  Davy, 
by  exposing  boracic  acid  to  a  powerful  galvanic  battery ;  but 
its  properties  were  first  investigated  by  Gay  Lussac  arid  The- 
nard,  who  obtained  it  in  greater  quantity  by  heating  boracic 
acid  with  potassium. 

The  easiest  method  of  obtaining  it  is  to  decompose  boro- 
ftuoride  of  potassium,  by  means  of  potassium  and  heat. 

Properties.  A  dark  olive-colored  solid,  without  taste  or 
odor ;  a  non-conductor  of  electricity  ;  sp.  gr.  nearly  2  ;  insolu- 
ble in  water,  alcohol,  ether,  and  oils  ;  does  not  decompose 
water  at  any  temperature,  and  may  be  subjected  to  intense 
heat  in  close  vessels  without  change  ;  heated  to  600°  in  the 
air,  it  ignites,  and  is  converted  into  boracic  acid.  When 


208  Boron  and  Oxygen. 

heated  with  nitric  acid,  or  with  any  substance  which  yields 
oxygen  freely,  it  passes  into  boracic  acid. 

Boron  and  Oxygen. 

Boracic  Acid.  Symb.  B-J-3O.  Equiv.  34.9.  Sp.  gr. 
1.479,  water  1.  This  substance  exists  in.  nature  in  small 
quantities  in  the  Lipari  Islands,  and  the  hot  springs  of  Lasso, 
in  the  Florentine  territory  ;  in  combination  with  soda,  in 
the  well-known  substance  borax,  the  biborate  of  soda,  us«-d 
by  smiths  as  a  flux.  It  is  also  a  constituent  of  the  minerals 
boracitc  and  datholite. 

Process.  To  a  solution  of  purified  borax  in  boiling  water, 
add  half  its  weight  of  sulphuric  acid,  diluted  with  an  equal 
quantity  of  water.  On  evaporation*  and  cooling,  shining 
crystals  of  boracic  acid  will  be  deposited  ;  it  may  be  purified 
by  repeated  solution  in  hot  water  and  crystallization.  This 
is  a  hydrate,  containing  1  eq.  of  acid  and  3  of  water.  The 
anhydrous  acid  may  be  obtained  by  heating  this  in  a  plati- 
num crucible. 

Properties.  The  hydrous  acid  exists  in  the  form  of  thin 
white  scales,  without  odor,  and  nearly  tasteless,  sparingly 
soluble  in  water,  which  reddens  vegetable  blue  colors,  and, 
like  the  alkalies,  turns  turmeric  paper  brown,  soluble  in  boil- 
ing alcohol,  and  gives  a  beautiful  green  color  to  flame. 

The  anhydrous  acid  is  a  hard,  colorless,  transparent  ghss 
absorbs  water  rapidly  from  the  air,  and  should  be  kept  in 
well-stopped  vials ;  exceedingly  fusible,  and  communicates 
this  property  to  the  substances  with  which  it  unites.  Hence 
its  use  in  the  arts  as  a  flux. 

Fig.  88. 

*  Fig.  88  represents  the  form  of  evaporating 
Hi.-itnf  ;  some  are  made  of  clay  and  sand,  oth- 
ers of  porcelain,  glass,  silver,  platinum,  and 
gold.  The  substance  to  be  evaporated  is 
poured  into  thorn,  and  they  are  placed  in  a 
sand  bath,  which  is  simply  a  quantity  of  com- 
mon sand  contained  in  an  iron  vessel,  and 
connected  generally  with  the  furnace  or  fire- 
place, so  as  to  be  kept  constantly  at  a  tem- 
perature below  the  boiling  point. 


Selenium.        •  209 


Boron  and  Chlorine. 

Terchloride  of  Boron.  Symb.  B-f  3C1.  Eq.  117.16.  Pro- 
duced by  the  spontaneous  combustion  of  boron  in  chlorine 
gas.  It  is  rapidly  absorbed  by  water,  and  unites  with  am- 
monia, forming  a  volatile  fluid.  It  is  also  formed,  according 
to  Despretz,  by  passing  dry  chlorine  gas  over  charcoal  and 
boracic  acid,  ignited  in  a  porjcelain  tube.  It  was  first 
noticed  by  Davy,  and  examined  by  Berzelius,  Dumas,  and 
Despretz. 

Boron  and  Fluorine. 

Fluoboric  Add.  Symb.  B.+  3F.  Equiv.  66.94.  Sp.gr. 
2.36:22.  Discovered  by  Gay  Lussac  and  Thenard,  in  1810. 

Process.  Mix  1  part  of  pure  boracic  acid  and  2  of  fluor- 
spar with  12  of  sulphuric  acid,  in  a  glass  flask,  and  apply  heat ; 
or  heat  a  strong  solution  of  hydrofluoric  and  boracic  acids  in 
a  metallic  retort. 

Properties.  A  colorless  gas,  of  a  penetrating,  pungent 
odor ;  extinguishes  flame,  reddens  litmus  powerfully,  and 
unites  with  bases  forming  salts  called  fluoborates. 

It  has  a  powerful  affinity  for  water,  which  absorbs  700 
volumes  of  the  gas;  becomes  hot,  fuming,  and  caustic; 
attacks  animal  and  vegetable  substances  with  great  energy. 
Some  doubt  yet  exists  concerning  its  true  nature. 

Boron  and  Sulphur. 

Sulphuret  of  Boron  is  formed,  according  to  Berzelius,  by 
burning  boron  in  the  vapor  of  sulphur.  The  product  is  a 
white,  opaque  mass,  readily  decomposed  by  water. 


SECT.  12.     SELENIUM. 
Symb.  Se.     Equiv.  39.6.     Sp.  gr.  4.32. 

Selenium  was  discovered  by  Berzelius,  in  1818,  and 
named  Selenium,  from  Selene,  the  moon,  because  he  at  first 
mistook  it  for  tellurium. 

Natural  History.     It  is  found  in  small  quantities  among 

18* 


210  Selenium. 

the  volcanic  products  of  the  Lipari  Islands,  in  Clausthal  in 
the  Hartz,  combined  with  lead,  cobalt,  silver,  mercury,  and 
copper.  fierzelius  obtained  it  from  the  iron  pyrites  of 
Fahlun. 

Process.  Mix  the  native  sulphuret  of  selenium  with  8 
times  its  weight  of  peroxide  of  manganese,  and  expose  it  to  a 
low  red  heat  in  a  glass  retort,  the  beak  of  which  dips  into 
water.  The  manganese  yields  its  oxygen  to  the  sulphur, 
and  the  selenium  sublimes  pure,  or  in  the  form  of  seleiimus 
acid. 

Properties.  A  brittle,  opaque  solid,  without  taste  or  odor ; 
its  lustre  is  metallic,  resembling  lead  in  the  mass,  but  the 
powder  has  a  deep  red  color  ;  softens  at  212°,  and  may  be 
<lr.t\vn  out  into  fine,  transparent  threads,  which  appear  red  by 
transmitted  light ;  becomes  fluid  a  little  above  212°,  and  boils 
at  650°,  yielding  an  inodorous  vapor  of  a  deep  yellow  color . 
sublirn.es,  in  close  vessels,  without  change,  and  cond. 
into  dark  globules,  or  into  a  cinnabar-red  powder,  if  the  ves- 
sels are  large.  Heated  in  the  open  air,  or  in  oxygen,  it  com- 
bines with  the  oxygen ;  under  the  blowpipe,  it  emits  the 
strong  odor  of  horseradish. 

Selenium  and  Oxygen. 

Oxide  of  Selenium  (Symb.  Se  +  O.  Equiv.  47.6)  is 
formed  by  heating  selenium  in  a  limited  quantity  of  air,  and 
washing  the  product  to  clear  it  from  selenious  acid.  It  is  a 
colorless  gas,  which  gives  the  peculiar  odor  to  the  selenium, 
when  burned  in  the  wick  of  a  lamp. 

Selenious  Acid  (Symb.  Se  +  2O.  Equiv.  55.6)  is  formed 
by  dissolving  selenium  in  nitrohydrochloric  acid.  On  evap- 
oration, the  acid  is  left  as  a  white,  crystalline  solid,  of  a  sour 
and  burning  taste;  dissolves  readily  in  water  and  alcohol, 
and  attracts  moisture  from  the  air.  It  has  distinct  acid 
properties,  and  its  salts  are  called  selenites.  It  is  decom- 
posed by  all  substances  which  have  a  strong  attraction  for 
oxygen. 


Compounds  of  Selenium.  211 

Seknic  Add  (Symb.  Se+3O.  Equiv.  63.6)  was  first 
noticed  by  M.  Nitzsch,  and  described  by  Mitscherlich  in 

1827. 

Process.  It  is  obtained  by  fusing  nitrate  of  potassa  or 
soda  with  selenium ;  a  metallic  seleniuret  with  selenious  acid, 
or  any  of  its  salts.  (For  process,  see  Turner,  6th  ed.  p.  209.) 

Properties.  A  colorless  liquid:  sp.  gr.  at  329°,  2.524;  at 
5123, 2.60.  It  is  decomposed  by  heat  at  536°,  and  is  resolved 
into  oxygen  and  selenious  acid ;  has  a  powerful  affinity  for 
water,  with  which  it  combines,  with  the  evolution  of  as  much 
caloric  as  sulphuric  acid  and  water.  It  dissolves  zinc,  iron, 
copper,  and  gold ;  unites  with  bases,  and  forms  salts  analo- 
gous, in  composition  and  form,  to  those  of  sulphuric  acid. 

Chloride  of  Selenium  is  a  white  solid,  obtained  by  placing 
selenium  in  chlorine  gas. 

Bromide  of  Selenium  is  an  orange-colored  solid;  soluble 
in  water,  and  obtained  by  dropping  selenium  into  bromine. 
The  combination  is  violent,  with  the  evolution  of  much  heat. 

Selenium  and  Hydrogen. 

Hydroselenic  Acid.  Symb.  Se  -f  H.  Eq.  41.  This  acid 
was  discovered  by  Berzelius,  and  some  doubt  exists  as  to  its 
composition. 

Process.  It  may  be  obtained  by  the  action  of  hydrochloric  acid  upon 
a  concentrated  solution  of  any  hydroseleniate. 

Properties.  A  colorless  gas,  with  an  odor  resembling  hy- 
drosulphuric  acid.  It  irritates  the  membrane  of  the  nose, 
exciting  catarrhal  symptoms,  and  produces  temporary  insen- 
sibility. Water  absorbs  it  readily,  and  the  solution  reddens 
litmus,  and  leaves  a  brown  stain  upon  the  skin.  On  exposure 
to  the  air,  it  is  decomposed,  but  decomposes  all  the  salts  of 
the  common  metals,  forming  seleniurets  of  the  metal. 

Selenium  and  Sulphur. 

Bisulphuret  of  Selenium  (Symb.  Se-|-2S.  Eq.  718)  was 
obtained  by  Berzelius,  by  adding  hydrosulphuric  acid  to  a 
solution  of  selenious  acid,  when  it  is  precipitated  as  an 
orange-colored  powder ;  fuses  at  212°,  sublimes  at  a  high 


212  Silicon. 

temperature  without  change ;  when  heated  in  the  open  air,  it 
inflames,  and  is  decomposed  by  nitrohydrochloric  acid. 

Seleniuret  of  Phosphorus,  or  Phosphuret  of  Selenium,  is 
prepared  in  the  same  manner  as  the  sulphuret  of  phosphorus. 
It  is  a  very  fusible  substance ;  imflammable,  and  decomposes 
water  slowly,  yielding  seleniuret  of  hydrogen,  and  one  of  the 
acids  of  phosphorus. 


SECT.  13.     SILICON. 
Symbol,  Si.     Equivalent,  22.5. 

Silicon  was  obtained  by  Berzelius,  in  1824,  by  the  action  of 
potassium  on  fluosilicic  acid  gas.  It  was  at  first  called  <ili- 
cium,  and  regarded  as  a  metal,  but  it  is  destitute  of  the  me- 
tallic properties. 

Properties.  Silicon  is  a  solid,  of  a  dark  brown  color,  and 
a  non-conductor  of  electricity. 

Before  ignition  it  is  not  oxidized,  or  dissolved  by  hot  sul- 
phuric or  nitrohydrochloric  acids,  but  is  soluble  in  hydro- 
fluoric acid,  and  in  a  hot,  concentrated  solution  of  can-tic 
potassa.  It  burns  readily  in  air,  and  vividly  in  oxygen  gas ; 
but  after  ignition,  it  is  insoluble  and  non-combustible.  It  is 
oxidized  by  heating  it  with  nitrate  of  potassa,  and  explodes 
when  dropped  upon  fused  hydrate  of  potassa,  soda,  or  baryta, 
in  consequence  of  the  evolution  of  hydrogen. 

Silicon  and  Oxygen. 

Silicic  Acid,  Silica.  Symb.  Si  +  3O.  Equiv.  22.5-}- 
24  =  46.5. 

Natural  History.  Silicic  acid,  also  called  silica,  siliceous 
earth,  and  silex,  constitutes  nearly  40  per  cent,  of  the  crust 
of  the  globe.  Hence  it  is  the  principal  ingredient  of  exten- 
sive mountain  masses,  of  sand,  and  of  several  minerals,  such 
as  quartz,  flint,  chalcedony,  rock-crystal,  etc.  It  is  the  most 
abundant  ingredient  in  nearly  all  soils. 

Process.  It  may  be  prepared  by  heating  rock-crystals,  and 
throwing  them,  red-hot,  into  cold  water. 


Compounds  of  Silicon.  213 

Properties.  When  reduced  to  powder,  it  is  white,  insipid, 
and  inodorous.  It  ia,  very  infusible,  requiring  the  heat  of  the 
compound  blowpipe  to  fuse  it;  insoluble  in  water,  unless 
presented  in  the  nascent  state ;  does  not  act  upon  test  paper, 
but  in  every  other  respect,  has  the  properties  of  an  acid.  Its 
combination  with  the  fixed  alkalies  is  effected  by  mixing 
pure  sand  with  carbonate  of  potassa.  If  3  parts  of  the  car- 
bonate to  1  of  sand  are  mingled,  the  fused  silicate  is  solu- 
ble in  water;  but  if  1  part  of  the  carbonate  to  3  of  sand 
be  employed  and  fused,  the  well-known  substance  glass  is 
formed,  which  is  transparent,  brittle,  insoluble  in  water,  and 
affected  by  no  acid  except  the  hydrofluoric. 

Every  kind  of  common  glass  is  a  silicate,  and  the  different 
varieties  are  due  to  the  proportions  of  the  constituents,  to  the 
nature  of  the  alkali,  or  the  ^presence  of  foreign  matter.  Thus 
green  bottle  glass  is  made  of  materials  containing  iron; 
Crown  glass,  of  pure  alkali  and  sand,  free  from  iron.  Plate 
glass,  for  mirrors,  is  made  of  the  purest  materials.  Flint  glass 
contains  red  lead;  and  sometimes  peroxide  of  manganese, 
or  nitre,  is  added-  to  oxidize  the  carbon  contained  in  the 
materials. 

Chloride  of  Silicon  (Symb.  Si  +  Cl.  Equiv.  57.92)  is 
prepared  by  burning  silicon  in  chlorine  gas.-  The  product  is 
a  limpid,  volatile  liquid,  flying  off  in  white  vapor  when  ex- 
posed to  the  air,  with  a  suffocating  odor  resembling  cyano- 
gen ;  boils  at  124°  Fahr. 

Bromide  of  Silicon  (Symb.  Si-f-Br.  Equiv.  100.6)  was  obtained  by 
Serullas,  in  the  same  manner  as  the  chloride.  It  is  a  very  dense,  color- 
less liquid,  emitting  dense  fumes. 

Suljthuret  of  Silicon  (Symb.  Si  -[-  S.  Equiv.  38.6)  is  formed  by  heat- 
ing silicon  in  the  vapor  of  sulphur.  It  is  a  white,  earthy  substance, 
instantly  converted  by  the  action  of  water  into  hydrosulphuric  and 
silicic  acids. 

Fivosilicic  Acid  (Symb.  Si-f-F.  Equiv.  41.18)  is  formed  by  bring- 
ing hydrofluoric  and  silicic  acids  into  contact.  It  is  a  colorless  gas, 
which  extinguishes  flame,  destroys  animals  immersed  in  it,  and  acts 
powerfully  upon  the  respiratory  organs.  Water  acts  upon  this  gas 
with  some  change  of  properties,  and  the  solution  is  called  silicohy- 
drofluoric  acid. 


214  Metals,  urith  their  Primary  Compounds. 

CHAPTER    II. 
CLASS  II.     METALS,  WITH  THEIR  PRIMARY  COMPOUNDS. 

General  Properties  of  Metals. 

Metals  arc  the  most  important  of  substances.  They  are 
distinguished  from  other  substances  by  the  following  prop- 
erties :  — 

1.  They  are  all  conductors  of  electricity  and  of  caloric. 

2.  When  combined  with  oxygen,  chlorine,  iodine,  sulphur, 
and  similar  substances,  and  subjected  to  the  voltaic  battery, 
they  always  go  to  the  negative  electrode  or  pole,  and  hence 
are  called  positive  electrics. 

3.  Metals  are  opaque ;  that  is,  they  do  not  permit  the  light 
to  pass  through  them,  although  reduced  to  thin  leaves. 

4.  They  are  good  reflectors  of  light,  and  possess  a  peculiar 
lustre,  which  is  termed  the  metallic  lustre.     Any  substance, 
which  has  the  above  properties,  may  be  regarded  as  a  metal. 

Metals  differ  greatly  in  their  Properties. 

1.  In  their  specific  gravity.     Most  of  the  metals  are  re- 
markable for  their  weight,  such  as  gold  and  platinum,  which 
are  more  than  nineteen  times  as  heavy  as  an  equal  bulk  of 
water;  while  some,  potassium  and  sodium,   are  lighter  than 
water. 

2.  In  their  malleability,  or  the  property  of  being  beaten 
into  thin  leaves  by    hammering.     Gold,  silver,  copper,  tin, 
platinum,  palladium,  cadmium,  lead,  zinc,  iron,  nickel,  po- 
tassium, sodium,  and  frozen  mercury,  are  malleable.     The 
others  are  malleable  only  in  a  slight  degree,  or,  like  arsenic, 
antimony,  and  bismuth,  brittle.     Gold  is  the  most  malleable 
of  metals;  one  grain   of  which  may  be   extended  so  as   to 
cover  fifty-two  square  inches  of  surface,  and  to  have  a  thick- 
ness not  exceeding  2^2^217  °f  an  mcn- 


General  Properties  of  Metals.  215 

3.  In  their  ductility,  or  the  property  of  being  drawn  out 
into  wires.     Most  of  the  malleable  metals    are  also  ductile, 
Gold,  silver,  platinum,  iron,  and  copper,  are  the  most  ductile 
Gold  wire  may  be  obtained  so  fine  that  it  shall  not  exceed 
•juW  °f  an  mcn  m  diameter,  and  platinum  7uihnr  of  an 
inch.     The  tenacity  of  a  metal  is  measured  by  the  weight 
which    a  wire   of  a  certain  diameter  can  support  without 
parting. 

4.  In  hardness.     Titanium,  manganese,  iron,  nickel,  cop- 
per, zinc,  and  palladium,  are  hard  metals.     Gold,  silver,  and 
platinum,  are   softer  than   these,  lead  still   softer,   and   po- 
tassium   and   sodium   yield   readily   to  the  pressure  of  the 
fingers. 

5.  In  their  structure.     Many  have  a  crystalline  structure. 
Iron  is  fibrous;  zinc,  bismuth,  and  antimony,  are  lamellated; 
gold,  silver,  and  copper,  are  found  naturally  in  crystals,  and 
others  may  be  made  to  assume  the  form  of  crystals,  when 
they  pass  gradually  from  a  liquid  to  a  solid  state.     Most  of 
them,  in  crystallizing,  assume  the  figure  of  a  cube,  the  reg- 
ular octohedron,  or  some  form  allied  to  it. 

6.  In  their  fusibility.     All  are  solid,  at  the  common  tem- 
perature of  the  atmosphere,  except  mercury,  which  is  solid 
at  -40°  Fahr.     Mercury,  potassium,  sodium,  cadmium,  tin, 
bismuth,  lead,  tellurium,  antimony,  and  probably  arsenic,  are 
fusible  below  red  heat.     The  rest  require  a  higher  tempera- 
ture to  fuse  them ;  and  some  of  these,  such  as  platinum,  ceri- 
um, rhodium,  and  columbium,  require  the  heat  of  the  com- 
pound blowpipe  to  render  them  liquid. 

7.  In  volatility.     Cadmium,  mercury,  arsenic,  tellurium, 
potassium,  sodium,  and  zinc,  are  volatilized  by  heat.     Most 
of  the  others  may  be  exposed  to  the  most  intense  heat  of  a 
smith's  forge,  without  being  converted  into  vapor. 

8.  In  their  affinity  for  the  other  simple  substances.     Metals 
generally  have  an  extensive  range  of  affinity;  hence  they 
are  rarely  found  in  the  earth  in  their  simple  or  pure  state,  but 
are  generally  combined  with  other  bodies,  especially  with 


216  Metals.  —  General  Properties. 

oxygen  and  sulphur,  in  which  state  they  are  said  to  be 
mineralized. 

It  is  a  remarkable  fact,  that  they  are  not  disposed  to  com- 
bine with  compound  bodies.  They  combine  with  each  other, 
and  with  other  simple  substances,  generally  in  a  few  definite 
proportions. 

They  all  combine  with  oxygen,  though  with  different  de- 
grees of  energy.  Iron  and  copper  are  slowly  oxidized  at 
common  temperatures,  while  gold  will  sustain  the  most  in- 
tense heat  of  furnaces  without  oxidation.  Potassium  and 
sodium  will  even  decompose  water,  to  obtain  the  oxygen,  the 
moment  they  come  in  contact  with  it.  In  all  these  cases, 
they  produce  the  phenomena  of  combustion.  Hence  th«»y 
are  said  to  be  combustible.  With  chlorine,  iodine,  bromine, 
etc.,  they  combine  with  more  or  less  energy,  giving  rise 
to  the  same  phenomena.  Some  unite  with  oxygen  in  one 
proportion  only,  but  most  have  two  ^r  three  degrees  of 
oxidation. 

Metallic  oxides  may  be  reduced  to  the  metallic  state  by 
heat,  by  the  united  agency  of  heat  and  combustible  matter, 
by  voltaic  electricity,  and  by  the  action  of  the  deoxidizing 
agents  on  metallic  solutions. 

Many  metals  form  acids  with  oxygen,  as  well  as  oxides; 
but  one  only,  arsenic,  is  capable  of  forming  an  acid,  and  not 
an  oxide. 

Many  of  the  metallic  oxides  combine  with  acids,  and 
form  salts,  and  generally  the  protoxide  is  the  only  saliji- 
able  base. 

Oxides  sometimes  combine  with  each  other,  and  form  defi- 
nite compounds.  The  action  of  the  metals  upon  the  simple 
non-metallic  substances  will  be  noticed  in  their  proper 
place. 

The  number  of  metals  is  forty-two ;  and  the  following  table 
contains  their  names,  with  the  date  at  which  they  were  dis- 
covered, and  the  names  of  the  chemists  by  whom  the  dis- 
covery was  made:  — 


Table  of  the  Discovery  of  Metals. 


217 


Names  of  Metala. 

Authors  of  the  Discovery. 

Dates  of  the 
Discovery 

Gold       .        .    •) 

Silver    .      . 

Iron 

Copper 

Known  to  the  Ancients. 

Mercury 

Lead      . 

Tin        .       . 

Antimony    . 

Described  by  Basil  Valentine  . 

1490. 

Bismuth 
JZinc 

Described  by  Agricola 
First  mentioned  by  Paracelsus 

1530. 
16th  century. 

Arsenic        .    ) 
Cobalt          .    5 

Brandt       ....     "•.•)); 

1733. 

Platinum 

Wood,  assay-master,  Jamaica 

1741. 

Nickel 

Cronstedt     

1751. 

Manganese 

Gahn  and  Scheele     . 

1774. 

Tungsten     . 

D'Elhuyart        .... 

1781. 

Tellurium    . 

Mci  Her       

1782. 

Molybdenum 

Hielm        

1782. 

I  run  mm 

1789. 

Titanium 

Gregor       .         .         .         .        *.  ; 

1791. 

Chromium 

Vauquelin          .         .         .     "T 

1797. 

Columbium 

Hatchett    

1802. 

Palladium    .    ) 
Rhodium      .    ) 

Wollaston          .         . 

1803. 

Indium 

Descotils  and  Smithson  Tennant 

1803. 

Osmium 

Smithson  Tennant     . 

1803. 

Cerium 

Hisinger  and  Berzelius     . 

1804. 

Potassium    .   ^ 

Sodium 

Barium         .     > 

Davy          .        . 

1807. 

Strontium    .    1 

Calcium       .   J 

Cadmium     . 

Stromeyer          .... 

1818. 

Lithium 

Arfwedson         .... 

1818. 

Zirconium 

Berzelius          .;»  -"x  -/   ••>  . 

1824. 

Aluminium     } 

Glucinium       > 

Wohler      

1828. 

Yttrium           ) 

Thorium 

Berzelius   

1829. 

Magnesium 

Bussy         .         .         .         .  •      . 

1829. 

Vanadium 

Sefstrom            .... 

1830. 

Latanium    . 

Mosander           .... 

1839. 

It  will  be  found  convenient,  in  studying  the  properties  of 
the  metals,  to  arrange  them  in  groups.  They  may  be  divided, 
for  this  purpose,  into  the  two  following  orders :  — 

Order  I.  Metals  which,  by  oxidation,  yield  alkalies  or  earths. 

Order  II.  Metals,  the  oxides  of  which  are  neither  alka- 
lies nor  earths. 

19 


218  Metals.  —  Potassium. 

ORDER  I.  includes  twelve  metals,  which  may  be  arranged 
in  three  sections  or  divisions  :  — 

Section  I.   Metallic  bases  of  the  alkalies.     These  are, 

Potassium,  Sodium,  Lithium. 

Section  2.  Metallic  bases  of  the  alkaline  earths.  These 
are, 

Barium,  Strontium,  Calcium,  Magnesium. 

Section  3.   Metallic  bases  of  the  earths.     These  are. 

Aluminium,  Yttrium,  Zirconium. 

Glucinium,  Thorium, 

ORDER  II.  The  metals  belonging  to  this  order  are  ar- 
ranged in  the  three  following  sections  :  — 

Section  1.    Metals  which  decompose  water  at  a  red  heat :  — 

Manganese,  Cadmium,  Cobalt, 

Iron,  Tin,  Nickel. 

Zinc, 

Section  2.  Metals  which  do  not  decompose  water  at  any 
temperature,  and  the  oxides  of  which  are  not  reduced  to  the 
metallic  state  by  the  sole  action  of  heat :  — 

Arsenic,  Columbium,  Titanium, 

Chromium,  Antimony,  Tellurium, 

Vanadium,  Uranium,  Copper, 

Molybdenum,  Cerium,  Lead. 

Tungsten,  Bismuth, 

Section  3.  Metals,  the  oxides  of  which  are  decomposed  by 
a  red  heat :  — 

Mercury,  Platinum,  Osmium, 

Silver,  Palladium,  Indium. 

Gold,  Rhodium,  T. 


SECT.  1.     METALLIC  BASES  OF  THE  ALKALIES. 
POTASSIUM.    Symb.  K.     Equiv.  39.15.    Sp.  gr.  0.865. 

History.  The  discovery  of  potassium,  or  kalium,  as  it 
was  at  first  called,  was  made  by  Davy,  in  1807,  and  consti- 
tutes an  era  in  the  history  of  chemical  philosophy,  as  it  led 


Properties  of  Potassium.  219 

to  the  discovery  of  the  metallic  bases  of  the  other  alkalies 
and  alkaline  earths,  and  to  the  decomposition  of  a  variety  of 
compounds  which  were  before  regarded  as  simple  bodies. 

The  discovery  was  made  by  subjecting  the  hydrate  of 
potassa  to  the  influence  of  a  powerful  galvanic  battery  of 
290  pair  of  plates;  oxygen  appeared  at  the  positive,  and  a 
small  globule  of  a  metallic  lustre  at  the  negative  pole,  which 
proved  to  be  the  metal  potassium. 

Process.  Potassium  is  obtained  in  small  quantities  by 
galvanism  ;  but  the  best  method  is  that  of  M.  Curaudau, 
which  was  improved  by  Brunner,  and  modified  by  Wohler. 
The  substance  employed  is  carbonate  of  potassa,  prepared 
by  heating  cream  of  tartar  to  redness  in  a  covered  crucible. 
This  is  raised  to  a  high  temperature,  in  connection  with 
charcoal,  in  an  iron  retort ;  the  oxygen  of  the  potassa  com- 
bines with  the  carbon,  and  the  potassium  distils  over. 

Properties.  Potassium,  at  common  temperatures,  is  a 
soft,  malleable  solid,  yielding  to  the  pressure  of  the  fingers, 
like  wax  ;  of  a  decidedly  metallic  lustre  ;  similar  tb  mercury 
in  color  ;  somewhat  fluid  at  70°,  and  perfectly  liquid  at  150°  ; 
cooled  to  32°,  it  is  brittle;  sublimes  at  a  low  red  heat  in 
close  vessels  secluded  from  the  air ;  a  good  conductor  of 
electricity  and  of  caloric. 

Ptut  its  most  remarkable  property  is  its  affinity  for  oxygen. 
It  oxiclizes  rapidly  in  the  air  or  oxygen  gas;  but  if  a  piece  be 
thrown  upon  water,  it  will  decompose  it  rapidly,  disengaging 
so  much  heat  that  the  potassium  takes  fire,  and  burns  with  a 
beautiful  purple  fame.  The  evolution  of  hydrogen  gas 
causes  it  to  move  about  upon  the  surface  of  the  water,  and, 
combining  with  the  potassium,  augments  the  brilliancy  of 
the  combustion. 

Exp.  Invert  a  wine-glass  filled  with  water  in  the  cistern,  and  in- 
troduce a  small  piece  of  potassium  ;  it  will  rapidly  decompose  the 
water,  and  the  escape  of  hydrogen  gas  will  displace  the  water  in  the 
glass.  This  gas  may  then  be  ignited. 

Exp.  Heat  a  small  piece  of  iron,  and  drop  upon  it  potassium;  then 
invert  over  it  a  jar  of  oxygen  gas. 

Exp.  Drop  a  piece  upon  ice,  and  it  will  instantly  inflame  ;  a  deep 
hole  is  made  in  the  ice,  containing  pure  potassa. 

Exp.   To  show  that  the  action  of  potassium  upon  water  produces  an 


220  Metals.  —  Compounds  of  Potassium. 

alkali,  drop  a  small  piece  into  a  bottle  containing  vegetable  infusion, 
and  it  will  instantly  turn  it  grr.cn.  In  consequence  of  its  affinity  for 
oxygen,  it  must  be  kept  under  naphtha,  or  the  essential  oil  of  copaiba. 

Remark.  In  the  description  of  the  metallic  compounds, 
the  abbreviations  symb.  and  equiv.  will  be  omitted,  and  the 
symbols  and  equivalents  placed  immediately  after  the  naim-j 
of  the  substances. 

Compounds  of  Potassium. 

Protoxide  of  Potassium,  (K  +  O.  47.15,)  commonly  called 
potash,  or  potassa,  is  always  formed  when  potassium  is  put 
into  water,  or  burned  in  oxygen  gas.  It  exists  in  nature  in 
the  minerals,  feldspar,  mica,  and  several  others ;  in  all  \ 
tables,  from  which  it  is  obtained  by  leaching  their  ashes,  and 
boiling  the  lye. 

Properties.  The  pure  potassa  is  a  white  solid,  very  caus- 
tic, possessing  powerful  alkaline  properties  ;  easily  fused  by 
heat,  but  not  decomposed ;  deliquesces  in  the  air,  and  hence 
is  very  soluble  in  water,  forming  with  it  a  hydrate,  which 
retains  the  water  under  the  most  intense  heat. 

The  Hydrate  of  Potassa  contains  1  eq.  of  water,  and  is 
similar  in  its  properties  to  the  anhydrous  potassa.  The 
aqueous  solution  of  the  hydrate,  called  aqua  potastrr,  inny 
be  prepared  by  decomposing  the  carbonate  with  lime. 

Exp.   Put  quick  lime,  with  half  its  weight  of  carbonate  of  p-  • 
dissolved  in  8  or  10  times  its  weight  of  water,  into  a  ch'.ui  inui  v  ss.  I, 
and  put  it  into  well-stopped  bottles,  to  exclude  the  air,  from  which  it 
will  absorb  carbonic  acid.     If  the  solution  is  pure,  it  will  not  effervesce 
with  acids. 

The  solid  hydrate  may  be  made  from'this  by  evaporation,  and  further 
purification  by  alcohol,  which  dissolves  only  the  pure  hydrate  ;  the 
alcohol  is  then  driven  off  by  heat.  This  was  formerly"  called  Inpis 
causticus,  but  the  colleges  of  Edinburgh  and  London  called  it  potassa. 
fusa. 

Tests.  Potassa  may  be  distinguished  from  all  other  sub- 
stances by  the  precipitates  thrown  down  from  its  salts  in 
solution. 

Exp.  1.  Take  any  of  the  salts  of  potassa  in  solution,  and  pour  into 
them  tartaric  acid  ;  a  white  precipitate  will  be  thrown  down  —  the  bi- 
tartrate  of  potassa. 


Compounds  of  Potassium.  221 

Exp.  2.  Chloride  of  platinum  will  give  a  yellow,  and  when  dissolved 
in  alcohol,  n  pale  yelloic,  precipitate. 

Exp.  3.  Alcoholic  solution  of  carbazotic  acid  throws  dowrt  yellow 
crystals  of  carbazotate  of  potassa.  This  is  the  most  delicate  test. 

Uses.  Potassa „ being  a  very  powerful  alkali,  is  of  great 
use  in  chemistry  and  the  arts.  It  forms  the  bases  of  most 
soaps;  the  crude  potash  is  employed  for  making  glass. 

Owing  to  its  affinity  for  carbonic  acid,  it  is  used  for  ab- 
stracting that  substance  from  gaseous  mixtures,  and  for 
depriving  them  of  moisture. 

T.rofidv  of  Potassium  (K  +  3O.  63.15)  is  formed  when 
potassium  is  burned  in  the  air  or  oxygen  gas.  It  is  an 
ormge-colored  substance,  caustic,  alkaline,  heavier  than 
pot  issium,  and  decomposed  by  galvanism  and  by  water  ;  by 
the  Litter  it  is  resolved  into  the  protoxide  and  oxygen  ;  fuses 
below  a  red  heat,  in  which  state  it  burns  vividly,  in  contact 
with  combustibles. 

Chloride  of  Potassium  (K  -j-  Cl.  74.57)  was  long  known  by  the 
ri.inus  '  febrifuge  salt  of  Sylvius,'  *  regenerated  sea-salt.' 

It  may  be  formed  by  the  spontaneous  combustion  of  potassium  in 
chlorine,  or  by  dissolving  potassium  in  hydrochloric  acid,  and  evapo- 
rating the  solution  slowly  to  dryness. 

Properties.  It  occurs  in  cubic  crystals,  colorless,  of  a 
salifif.  and  bitter  taste,  insoluble  in  alcohol,  and  soluble  in  3 
parts  of  water  at  60°,  and  in  less  at  212°  Fahr. 

.     / >dide  of  Potassium  (K-f-I-  165.45)  is  formed  by  heating  potassium 
with  iodine,  or  by  heating  the  iodate  of  potassa. 

Properties.  Fuses  readily,  and  is  converted  into  vapor 
below  a  red  heat ;  deliquesces  in  air  ;  very  soluble  HI  water  ; 
dissolves  in  strong  alcohol,  and,  by  evaporating  the  solution, 
yields  colorless  cubic  crystals  of  iodide  of  potassium. 

Bromide  of  Potassium,  (K-f-Br.  117.55,)  formed  by  a 
process  similar  to  that  for  the  iodide,  (using  bromine  instead 
of  iodine,)  and  has  similar  properties;  very  soluble  in  water, 
which,  by  evaporation,  yields  anhydrous  cubic  crystals; 
easily  fused,  and  decrepitates,  like  sea-salt,  when  heated. 

Exp.  Put  a  small  piece  of  potassium  into  a  wine-glass  containing  a 
few  drops  of  bromine ;  the  two  bodies  will  combine  with  explosive 
violence. 

Fluoride   of  Potassium    (K  +  F.    57.83)    is   formed  by 
19* 


222  Metals.  —  Compounds  of  Potassium 

merely  saturating  hydrofluoric  acid  with  carbonate  of  potassa, 
evaporating  to  dryness,  and  igniting  to  expel  excess  of  acid. 

Properties.  It  has  a  sharp,  saline  taste,  alkaline  to  the 
test  papers,  soluble  in  water,  and  the  solution  acts  on  glass. 
It  is  obtained  from  its  solution,  by  evaporation  at  100°,  in 
cubes  or  rectangular  four-sidrd pritmf,  nry  (/i/if/m.«tut. 

Hydurct  of  Potassium.  Discovered  by  Gay  Lussac  aud 
Thenard,  and  may  be  formed  by  heating  potassium  in  hydro- 
gen gas.  It  is  a  gray  solid,  readily  decomposed  by  heat  or 
water.  Gaseous  hyduret  of  potassium  is  produced  when 
hydrate  of  potassa  is  decomposed  by  iron,  at  a  white  hr.it. 
It  is  a  colorless  gas,  and  burns  spontaneously  in  air  or  oxy- 
gen gas,  but  loses  its  inflammability  by  standing  over  mercury. 

Niturrt  of  Potassium  consists,  according  to  Thenard,  of  100  parts  of 
potassium  to  Il.TiteJ  of  nitrogen,  and  is  formed  by  lu-atin^  potassium 
with  amtnoniacal  gas. 

Sulphurtts  of  Potassium.  These  are  five  in  number,  de- 
pendent on  the  quantity  of  sulphur. 


The  Protosulphuret  of  Potassium    (K-f  S.   55.25)    is   prepared    by 
irning  potassium  and  sulphur  in  the  air,  or  by  decomposing  tl, 
phate  of  potassa  by  charcoal  or  hydrogen  gas  at  a  red  heat.     :>!,.v  «! 


with  powdered  charcoal,  it  kindles  spontaneously. 

The  Bisulphuret  of  Potassium  (K-J-2S.  71.35)  is  formed  by  re- 
posing a  saturated  alcoholic  solution  of  hydrosulphate  of  sulplmn  I  of 
potassium,  until  a  pellicle  begins  to  form,  and  then  evaporating  to 
dryness. 

The  Terrulphvret  of  Potassium  (K  +  S.  87.45)  is  formed  by  hmiitur 
carbonate  of  potassa  to  low  redness,  with  half  its  weight  of  sulphur, 
known  by  the  name  of  liver  of  sulphur. 

The  Qutnlrosulphurct  of  Potassivm  (K-J-4S.  103.55)  is  prepared  \v 
transmitting  the  vapor  of  bisulphuret  of  carbon  over  sulphate  of  potassa 
at  a  red  heat,  until  carbonic  acid  gas  ceases  to  be  disengaged. 

The  Quintosulphuret  of  Potassium  (K-f-5S.  11?U>5)  is  formed  by 
fusing  carbonate  of  potassa  with  its  own  weight  of  sulphur. 

The  properties  of  the  four  last  compounds  are  similar ; 
they  are  deliquescent,  have  a  sulphureous  odor,  and  are 
soluble  in  water.  A  solution  of  the  last  dissolves  sulphur, 
and  renders  it  probable  that  other  compounds  may  be 
formed. 

Phosphurcts  of  Potassium.  Several  compounds  exist,  but 
their  composition  is  unknown.  Obtained  by  burning  potas- 
sium in  phosphureted  hydrogen. 

Sehniuret  of  Potassium.  Formed  by  fusing  potassium  and 
selenium  together.  They  combine  with  explosive  violence, 


Sodium.  223 

and  a  crystalline,  fusible  compound  results,  of  an  iron-gray 
color,  and  metallic  lustre. 

Cyanurct  of  potassium  (K-{-Cy.  65.54)  is  formed  by  heating  to  red- 
ness the  anhydrous  ferric  ijanuret  of  potassium  in  an  iron  bottle. 

Properties.  Easily  fused,  and  crystallizes  in  colorless 
cubes  ;  pungent  and  alkaline  to  the  taste,  and  poisonous,  act- 
ing like  the  hydrocyanic  acid  ;  deliquescent,  and  very  solu- 
ble in  water;  used  sometimes  as  a  medicine. 

Sulplwcyanurct  'if  Potassium      K  -(-  Cy.  97.74. 


SODIUM.     Symb.  Na.     Equiv.  23.3.     Sp.  gr.  0.972. 

Sodium  was  discovered  by  Sir  H.  Davy,  in  1807,  a  few 
days  after  the  discovery  of  potassium,  and  by  a  similar 
process. 

Process.  It  may  be  obtained  in  small  quantities  by  gal- 
vanism. But  the  process  of  obtaining  it  from  soda,  now 
generally  practised,  is  precisely  the  same  as  that  for  potas- 
sium. 

Properties.  Sodium  resembles  potassium  in  many  of  its 
properties.  It  is  a  white,  opaque  solid,  of  a  metallic  lustre, 
resembling  silver :  yields  readily  to  the  pressure  of  the 
fingers,  and  may  be  formed  readily  into  leaves ;  fuses  at  200° 
Falir.,  and  is  vaporized  at  a  red  heat. 

Sodium  has  so  strong  an  affinity  for  oxygen  that  it  rapidly 
decomposes  water  to  obtain  it,  but  does  not  inflame  unless 
the  water  is  heated,  in  which  case  it  throws  out  beautiful 
scintillations,  often  with  violent  combustion. 

Exp.  Thrown  upon  water,  it  moves  about  upon  its  surface,  having 
the  appearance  of  a  silver  ball,  gradually  growing  less  till  the  whole 
disappears. 

Exp.  Drop  a  piece  of  sodium  into  a  test-tube  partly  filled  with  warm 
water;  it  will  soon  burst  into  a  flame,  and  often  explode  with  violence. 

It  oxidizes  in  the  air  or  oxygen  gas,  but  not  so  rapidly  as 
potassium ;  hence,  like  that  metal,  it  must  be  kept  under 
naphtha.  The  product  of  its  combustion  in  oxygen,  and  its 
action  upon  water,  is  soda,  the  alkaline  properties  of  which 
may  be  tested  by  dropping  a  small  piece  of  the  metal  into  a 
bottle  containing  a  vegetable  infusion. 


224  Metals.  —  Compounds  of  Sodium 

Compounds  of  Sodium. 

Protoxide  of  Sodium,  (NaO.  31.3,)  commonly  called  soda, 
and  by  the  Germans  natron,  is  formed  by  the  oxidation  of 
sodium  in  air  or  water. 

Properties.  A  gray  solid,  similar  to  potassa,  which  it 
resembles  in  most  of  its  properties ;  very  caustic,  and  has 
powerful  alkaline  properties. 

The  hydrate  has  I  eq.  of  water,  and  is  easily  fused.  In 
other  respects,  it  is  similar  to  the  anhydrous  soda;  absorbs 
carbonic  acid  from  the  air,  and  passes  into  carbonate. 

It  is  distinguished  from  other  alkaline  bases  by  yield  inn, 
with  sulphuric  acid,  the  well-known  substance  called  (j/tm- 
ber's  salts.  All  its  salt*  are  soluble  in  water,  and  are  riot 
precipitated  by  any  re-agent,  and  give  a  rich  color  to  the 
blowpipe  flame.  The  soda  of  commerce  is  generally  a  car- 
bonate prepared  from  the  ashes  of  marine  plants,  in  the 
same  manner  as  potash  is  from  land  plants. 

Uses.  Employed  for  the  manufacture  of  hard  son ps,  ;m;l 
for  culinary  and  medical  purposes. 

Sesquioride  of  Sodium  (2Na-f-3O.  70.6)  is  formed  when 
sodium  is  heated  to  redness,  in  excess  of  oxygen  gas.  It  h  «•< 
an  orange  color,  but  no  arid  or  alkaline  properties.  It  is 
resolved  by  water  into  soda  and  oxygen. 

Chloride  of  Sodium.  Na  +  CJ.  58.72.  This  substance  is 
formed  by  burning  sodium  in  chlorine  gas,  or  by  saturating 
soda  with  hydrochloric  acid,  and  evaporating  to  dryness.  It 
is  a  very  abundant  natural  product,  under  the  name  of  rork 
salt.  It  exists  in  sea-water  and  salt-springs,  from  which  it 
is  obtained  by  evaporation.  Great  quantities  are  manufac- 
tured on  the  sea-coast  of  New  England,  and  at  Salina,  N.  Y. 
The  water  at  the  latter  place,  according  to  the  analysis  of 
Beck,  contains  one  seventh  of  its  weight  of  pure  dry  chloride 
of  sodium. 

Properties.  A  well-known  solid,  crystallizing  in  regular 
cubes,  and  by  sudden  evaporation,  in  hollow,  quadrangular 
pyramids.  It  is  dissolved  in  2J  times  its  weight  of  water,  at 


Compounds  of  Sodium.  225 

69°  Fahr. ;  gradually  fuses  when  heated,  and  decrepitates 
when  thrown  into  the  fire  ;  is  decomposed  by  carbonate  of 
potassa  and  nitric  acid.  The  different  kinds  of  salt,  such,  as 
stored,  fishery,  bay,  &c.,  arise  from  its  different  forms,  and 
not  from  a  difference  of  chemical  constitution.  It  contains 
small  quantities  of  sulphate  of  magnesia  and  lime,  and  chlo- 
ride of  magnesium. 

Uses.  The  utility  of  salt  depends  on  its  property  of  pre- 
serving animal  and  vegetable  substances  from  putrescence. 

Iodide  of  Sodium,  (Na-f-1-  149.0,)  prepared  in  the  same  manner 
as  the  iodide  of  potassium,  exists  in  sea-water,  salt-springs,  and  in  the 
residual  liquor  from  kelp. 

Bromide  of  Sodium,  (Na-f-Br.  101.7,)  analogous  to  sea-salt,  exists 
in  sea-water  and  salt-springs,  and  crystallizes  in  cubes. 

Fluoride  of  Sodium  (Na-f-F.  41.98)  is  formed  by  neutralizing  hydro- 
fluoric acid  with  soda  ;  crystallizes  in  cubes,  and  when  carbonate  of 
soda  is  present,  in  octohedrons.  Nearly  insoluble  in  alcohol ;  soluble  in 
twenty-five  times  its  weight  of  water ;  attacks  glass  vessels  when 
evaporated  in  them  —  a  property  which  is  common  to  most  of  the  com- 
pounds of  fluorine. 

Sulphure/.  of  Sodium  (Na-f-S.  39.4)  is  obtained  in  the  same  manner 
as  the  protosulphuret  of  potassa,  and  has  similar  properties. 

The  Cijanuret  of  Sodium  (Na-f-Cy.  49.69)  and  the  Sulphocyanuret 
of  Sodium  (Na-f-CyS2.  81.89)  are  similar  to  the  corresponding  com- 
pounds of  potassium. 

Chloride  of  Soda  is  prepared  by  passing  a  current  of  chlo- 
rine gas  into  a  cold  solution  of  caustic  soda.  This  liquor 
has  received  the  name  of  Lab arr aqua' s  Disinfecting  Soda 
Liquid,  and  is  used  extensively  in  the  arts,  and  in  med- 
icine. 

Properties.  A  liquid  of  a  pale  yellow  color,  with  slight 
odor  of  chlorine.  Its  taste  is  sharp,  saline,  and  but  little 
alkaline;  reddens  turmeric,  and  then  bleaches  it.  When 
evaporated,  it  yields  damp  crystals  ;  decomposed  by  exposure 
to  the  air. 

Uses.  It  may  be  used  for  all  the  purposes  of  bleaching  to 
which  chlorine  was  formerly  applied,  in  medicine  to  purify 
apartments,  dissecting-rooms,  for  destroying  the  fetor  of 
ulcers,  and  for  removing  the  offensive  odors  of-sewers,  drains, 
and  all  kinds  of  animal  putrescence. 

Alloy  of  Sodium  arid  Potassium.     10  parts  of  potassium, 


226  Metals.  — Lithium. 

and  1  of  sodium,  form  an  ayoy.which  is  liquid  at  zero,  Fahr., 
and  is  lighter  than  naphtha,  or  rectified  petroleum. 


LITHIUM.     Symb.  L.     Equiv.  6.44. 

This  substance  was  obtained  by  Davy,  by  means  of  gal- 
vanism, as  a  white-colored  metal,  like  sodium  ;  but  it  oxidized 
so  rapidly  that  he  was  unable  to  examine  its  properties. 

Compounds  of  Lithium. 

Protoxide  of  Lithium,  Lit/tin,  (L-J-O.  14.44,)  was  dis- 
covered, in  1818,  by  M.  Arfwedson,  in  the  mineral  petalite; 
it  exists  in  spotlumene,  lepidolite,  and  several  varieties  of 
mica. 

Process.  One  part  of  petalite  jo  two  of  fluor-spar  are 
finely  pulverized,  and  the  mixture  heated  with  four  times 
its  weight  of  sulphuric  acid,  till  the  acid  vapors  are  <li-<-n- 
gaged.  Sulphate  of  lithia  and  alumina  are  formed.  These 
salts  are  then  dissolved  in  water,  and  boiled  with  pure  am- 
monia, to  precipitate  the  alumina ;  filter  and  evaporate  to  dry- 
ness,  and  then  expel  the  sulphate  of  ammonia  by  a  red  heat. 
The  result  is  a  pure  sulphate  of  lithia,  which  must  be 
decomposed  by  acetate  of  baryta,  and  the  acetate,  by  a  red 
heat,  is  converted  into  the  carbonate,  and  this  reduced  to  the 
caustic  hydrate,  by  boiling  it  with  lime. 

Properties.  Similar  to  potassa  and  soda  in  its  alkalinity 
and  chemical  relations.  It  is  distinguished  from  them  by  its 
greater  neutralizing  power ;  when  exposed  to  the  air,  it  ab- 
sorbs carbonic  acid,  and  becomes  opaque. 

Chloride  of  Lithium  (L-f-Cl.  41.86)  is  obtained  by  dissolving  lithia 
in  hydrochloric  acid,  evaporating  to  dryness,  and  fusing  the  residue. 

Properties.  A  white,  semi-transparent  solid,  and,  like 
the  chlorides  of  potassium  and  sodium,  forms,  by  evaporation, 
colorless,  anhydrous,  cubic  crystals,  which  differ  from  those 
chlorides  in  being  very  deliquescent,  dissolving  freely  in 
water  and  alcohol,  and  tinging  the  flame  of  alcohol  red. 

Fluoride  of  Lithium,  (L-|-F.  25.12,)  prepared  by  dissolving  litbia  in 
hydrofluoric  acid,  and  is  a  very  fusible  solid. 


Barium.  227 


SECT.  2      METALLIC  BASES  OF  THE  ALKALINE  EARTHS. 

BARIUM. '  Symb.  Ba.     Equiv.  68.7. 

Barium  was  discovered  by  Davy,  in  1808. 

Process.  The  process  consisted  in  forming  the  carbonate 
of  baryta  into  a  paste  with  water,  placing  a  globule  of  mer- 
cury in  a  small  hallow  made  in  its  surface,  and  laying  the 
paste  on  a  platinum  tray,  which  communicated  with  the  posi- 
tive pole  of  a  galvanic  battery  of  100  double  plates,  while  the 
negative  wire  was  in  contact  with  the  mercury.  The  baryta 
was  decomposed,  and  its  barium  entered  into  combination 
with  the  mercury.  This  amalgam  was  heated  in  a  vessel 
free  from  air,  by  which  means  the  mercury  was  expelled, 
and  the  barium  obtained  in  a  pure  state.  —  T. 

Properties.  The  metal,  thus  obtained,  has  a  dark  gray 
color,  with  a  lustre  inferior  to  cast  iron.  It  is  much  heavier 
than  water  ;  it  even  sinks  in  sulphuric  acid.  Its  attraction 
for  oxygen  is  scarcely  less  than  that  of  the  preceding  metals ; 
is  converted  into  baryta  by  exposure  to  the  air  ;  decomposes 
water  with  effervescence,  from  the  escape  of  hydrogen  gas. 
It  has  been  obtained  but  in  small  quantities,  and  its  proper- 
ties are  not  accurately  denned. 

Compounds  of  Barium. 

Protoxide  of  Barium,  or  Baryta,  (Ba-J-O.  76$,)  was 
discovered  by  Scheele,  in  1774,  and  called  barytes  or  baryta, 
from  the  great  density  of  its  compounds. 

Process.  It  is  the  sole  product  of  the  oxidation  of  barium 
in  the  air  and  in  water.  It  is  also  obtained  by  exposing  the 
nitrate  of  baryta  to  a  red  heat,  or  the  carbonate,  mixed  with 
charcoal,  to  an  intense  white  heat. 

Properties.  Baryta  is  a  gray  powder,  (sp.  gr.  4,)  very  dif- 
ficult of  fusion  ;  has  a  sharp,  caustic,  alkaline  taste,  with 
other  alkaline  properties ;  insoluble  in  alcohol,  but  has  a 
strong  affinity  for  water,  and  slacks  like  lime,  but  with  the 
evolution  of  more  intense  heat,  and  is  converted  into  a  white, 
bulky  hydrate,  which  fuses  at  a  red  heat,  but  cannot  be 


228  Metals.  —  Compounds  of  Barium. 

deprived  of  its  water  at  the  highest  temperature  of  a  smith's 
forge.  A  saturated  solution  yields,  on  evaporation,  trans- 
parent, flattened,  prismatic  crystals,  containing  10  atoms  of 
water  to  1  of  baryta. 

This  solution  is  an  excellent  test  of  carbonic  acid,  or  other 
gaseous  mixtures  in  the  atmosphere.  The  acid  gives  a 
milky  appearance  to  the  clear  solution,  due  to  the  solid  car- 
bonate of  baryta,  which  is  precipitated. 

Distinguished  by  the  fact,  that  all  its  soluble  salts  are 
precipitated  by  alkaline  carbonates,  and  by  the  insoluble 
sulphate,  which  latter  cannot  be  separated  by  any  other  acid. 

Binoxidt  of  Barium  (Ba-|--O.  84.7)  is  formed  by  conducting  dry 
oxygen  gas  over  pure  baryta,  at  a  red  heat.  It  is  a  grayish-white  sub- 
stance, employed  by  Thenard  in  obtaining  the  binoxide  of  hydro 

Chloride  of  Barium  (Ba-fCl.  104.12)  is  prepared  by  decomposing  a 
solution  of  sulphu ret  or  barium  with  hydrochloric  acid,  or  by  conduct- 
ing chlorine  gas  over  baryta,  at  a  red  heat.  On  concentrating  the  solu- 
tion, the  chloride  crystallizes  in  flat,  four-sided  tables,  beveled  at  the 
edges  like  crystals  of  heavy-spar.  They  consist  of  1  eq.  of  the  chlo- 
ride to  2  of  water.  ,'  ..>  **.* 

Properties.     Pungent  and  acrid  to  the  taste.     The  n 
tals  do  not  change  in  moist  air  ;  but  in  a  very  dry  air,  ;. 
they   lose  their  water  of  crystallization,   and   are  rendered 
anhydrous  at  a  full  red  heat ;    decomposed  by  sulphuric  acid 
and  alkaline  carbonates. 

Iodide  of  Barium  (Ba-f-I-  195)  is  formed  by  acting;  on 
baryta  with  hydriodic  acid,  and  evaporating  the  solution. 
Soluble  in  water,  and  forms  colorless,  needle-shaped  crystals. 

Bromide  of  litirinm  (Ba-f-Br.  147.1)  is  prepared  by 
boiling  protobromide  of  iron  with  moist  carbonate  of  baryta, 
evaporating  the  filtered  solution,  and  healing  the  residue  to 
redness.  The  product  crystallizes,  by  careful  evaporation, 
in  white  rhombic  prisms,  which  have  a  bitter  taste,  are 
slightly  deliquescent,  and  soluble  in  water  and  alcohol.  —  T. 

Fluoride  of  Barium  (Ba  +  F.  87.38)  is  prepared  by 
digesting  moist  carbonate  of  baryta  in  hydrofluoric  acid.  It 
is  a  white  powder,  soluble  in  nitric  and  hydrochloric  acids. 

Sulphurct  of  Barium  (Ba  +  S.  84.8)  is  prepared  by  pass- 
ing dry  hydrosulphuric  acid  over  pure  baryta,  at  a  red  heat. 
It  dissolves  readily  in  hot  water,  and  deposits  colorless 
crystals  on  cooling.  It  may  be  employed  for  obtaining  pure 
baryta  by  a  process  described  by  Turner,  5th  ed.  p.  308. 


Strontium, 

Cyanurct  of  Barium  (Ba-j-Cy.  95.09)  is  procured  by 
the  action  of  hydrocyanic  acid  on  baryta.  It  is  slightly 
soluble  in  water,  has  an  alkaline  reaction,  and  is  decomposed 
by  the  carbonic  acid  of  the  air. 

Sulphocyanuret  of  Barium  (Ba  +  CyS2.  127.29)  is  ob- 
tained in  the  same  way  as  the  sulphocyanuret  of  potassium. 
It  is  very  soluble  in  water,  and  crystallizes  in  beautiful 
needles,  slightly  deliquescent. 

Phosphuret  of  Barium  is  formed  by  heating  to  redness  anhydrous 
caustic  baryta,  and  throwing  into  it  pieces  of  phosphorus.  It  decora- 
poses  water,  and  forms  phosphuret  of  hydrogen. 


STRONTIUM.     Symb.  Sr.     Equiv.  43.8. 

Strontium  was  discovered  by  a  process  similar  to  that  for 
barium,  which  it  resembles  in  most  of  its  properties ;  oxi- 
dizes in  the  air  ;  decomposes  water,  by  which  process  it  is 
converted  into  strontia. 

Compounds  of  Strontium. 

Protoxide  of  Strontium  (Sr-{-O.  51.8)  was  discovered 
by  Dr.  Hope,  in  1792 ;  also  by  Klaproth. 

Process.  It  was  formerly  extracted  from  strontianite,  (a 
carbonate  of  strontia,)  found  at  Strontian,  in  Scotland  ; 
hence  its  name.  It  may  be  prepared  from  the  nitrate  or 
carbonate  of  strontia,  in  the  same  manner  as  baryta. 

Properties.  It  resembles  baryta  in  most  of  its  properties. 
A  gray  substance,  pungent  and  acrid  to  the  taste ;  slacked 
with  water,  it  produces  intense  heat,  and  is  converted  into  a 
hydrate  which  fuses  readily,  but  the  highest  temperature  of- 
a  blast  furnace  will  not  separate  the  water;  soluble  in  boil- 
ing water,  and  crystallizes  on  cooling.  The  solution,  like 
baryta,  is  an  excellent  test  of  carbonic  acid. 

Peroxide  of  Strontium  (Sr-|-2O.  59.8)  is  prepared  in  the 
same  way  as  the  peroxide  of  barium,  and,  like  it,  is  em- 
ployed to  form  binoxide  of  hydrogen  ;  decomposed  by  dilute 
acids  into  strontia  and  oxygen.  It  is  white,  of  a  brilliant 
lustre,  inodorous,  and  nearly  tasteless. 

Chloride  of  Strontium  (Sr-|-Cl.  79.22)  is  obtained  in  a 
manner  precisely  similar  to  the  chloride  of  barium;  crys- 
20 


230  Mttals.  —  Calcium      \ 

tallizes  from  its  solutions  in  colorless  prismatic  cry 
which  are  distinguished  from  baryta  by  being  soluble  in  twice 
their  weight  of  water  at  60°,  and  by  the  red.  tinge  whirh  it 
gives  to  the  flame  of  an  alcoholic  solution.  The  anhydrous 
chloride  fuses  at  a  red  heat,  and  yields  a  white,  crystalline, 
brittle  mass  on  cooling.  —  T. 

Iodide  of  Strontium  (Sr-}-I.  1 70.  H  is  prepared  in  the  same  manner 
as  iodide  of  barium.  It  is  very  soluble  in  water,  fuses  without  decom- 
position in  close  vessels,  but  is  resolved  into  iodine  and  strontia,  by  a 
red  heat,  in  the  open  air. 

Fluoride  of  Strontium  (Sr-f-F.  02.48)  is  obtained  in  the  same  way  as 
the  fluoride  of  barium.  It  is  a  white  powder,  sparingly  soluble. 

Protosulphuret  of  Strontium  *(Sr  -f-  S.  59.9)  is  similar  in  its  pn»j>rr- 
ties,  and  modes  of  preparation,  to  the  corresponding  compound  of 
barium 

CALCIUM.     Symb.  Ca.    Equiv.  20.5. 

Calcium  was  discovered  by  Davy,  in   1808,  by  expo 
lime  to  the  action  of  the  galvanic  battery. 

Properties.  It  is  of  a  whiter  color  than  barium,  and  is 
converted  into  lime  by  oxidation.  Its  other  properties  arc 
unknown. 

Compounds  of  Calcium. 

Protoxide  of  Calcium  (Ca  -j-  O.  28.5)  is  generally  obtained 
by  burning  common  limestone  (carbonate  of  lime)  in  kilns, 
for  three  or  four  days,  to  expel  the  carbonic  aci<l.  It  is 
then  called  Kme,  or  quick  lime.  The  purest  lime  is  prepared 
from  the  Iceland  spar,  or  Carrara  marble. 

Properties.  A  brittle,  grayish-white,  earthy  solid,  of  an 
acrid,  caustic,  and  alkaline  taste ;  sp.  gr.  2.3 ;  difficult  of  fusion, 
but  promotes  the  fusion  of  other  bodies,  and  is  hence 
as  a  flux  in  smelting  the  ores  of  the  metals.  It  has  a  strong 
affinity  for  water,  with  which  it  combines  with  the  disengage- 
ment of  heat,  and  forms  the  hydrate  —  a  bulky,  white  sub- 
stance, called  slacked  lime.  This  parts  with  its  water  at  a 
red  heat,  and  is  more  soluble  in  cold  than  in  hot  water. 

Lime  Water.  This  is  simply  a  solution  of  the  hydrate,  and 
possesses  similar  properties,  absorbs  carbonic  acid  from  the 
air,  and  should  therefore  be  kept  in  close  vessels.  It  is  a 


Compounds  of  Calcium.  231 

most  delicate  test  of  carbonic  acid  —  a  property  already  no- 
ticed under  carbon. 

Uses.  The  uses  of  lime  are  well  known  for  a  cement,  for 
plaster,  and  as  an  anti-acid  in  medicine ;  a  substance  almost 
indispensable  in  every  civilized  country,  and  hence  the  Cre- 
ator has  made  it  very  abundant  and  widely  diffused,  (the 
carbonate  forming  $  part  of  the  crust  of  the  globe.) 

Peroxide  of  Calcium  (Ca-{-2O.  36.5)  is  similar  in  prop- 
erties, and  in  the  mode  of  preparation,  to  the  peroxide  of 
barium. 

Chloride  of  Calcium  (Ca  -f-  Cl.  55.92)  exists  in  sea-water 
and  some  saline  springs,  and  may  be  formed  by  dissolving 
marble  in  hydrochloric  acid.  On  evaporation,  the  solution 
yields  colorless  prismatic  crystals,  which  consist  of  10  equiv. 
of  water  to  1  of  the  chloride ;  these  are  rendered  anhydrous 
by  heat,  and  fuse  at  a  red  heat,  but  absorb  the  water  again 
from  the  air,  and  deliquesce,  owing  to  their  strong  attraction 
for  water.  It  is  much  used  for  freezing  mixtures  with  snow. 
Soluble  in  alcohol,  with  which  it  forms  a  definite  compound. 

Iodide  of  Calcium  (Ca  -f-  I.  146.8)  is  prepared  by  digesting 
hydrate  of  lime  with  protoxide  of  iron.  It  is  a  white,  fusible 
compound,  deliquescent,  and  very  soluble  in  water ;  the  solu- 
tion will  dissolve  a  large  quantity  of  iodine,  and,  on  evapo- 
ration, yield  the  periodide  of  calcium,  in  black  prismatic 
crystals. 

Bromide  of  Calcium  (Ca-|-Br.  08.9)  is  prepared  in  the 
same  manner  as  the  iodide,  which  it  resembles  in  its  prop- 
erties. 

Fluoride  of  Calcium.  Ca-f-F.  39.18.  This  is  an  abundant 
natural  product,  generally  called  fluor-spar  or  Derbyshire 
spar.  It  occurs  in  beautiful  cubic  crystals,  the  primary  form 
of  which  is  an  octohedron,  used  extensively  for  ornamental 
purposes,  and  is  justly  celebrated  for  the  variety  and  beauty 
of  its  colors  ;  fuses  at  a  red  heat,  insoluble  in  water,  and  is 
decomposed  by  sulphuric  acid;  thrown  in  coarse  powder  on 
hot  iron,  it  emits  beautiful  phosphorescent  light,  varying  from 
red  to  purple  and  green. 

Proto  sulphur  et  of  Calcium  (Ca-J-S.  36.6)  may  be  pre- 
pared by  exposing  sulphate  of  lime  to  a  strong  heat  in  a 
charcoal  crucible.  It  is  white,  with  a  reddish  tint,  and  pos- 
sesses the  remarkable  property  of  becoming  phosphorescent 
by  exposure  to  the  light.  It  is  the  essential  ingredient  in 
Canton's  phosphorus. 


232  Metals.  —  Magnesium. 

Bisulphuret  of  Calcium  (Ca-f  2S.  52.7')  occurs  in  orange-colored 
crystals,  prepared  by  boiling  3  parts  of  slacked  lime,  1  of  sulphur,  and 
20  of  water,  for  a  few  hours,  and,  setting  the  solution  aside  in  bottles 
corked  tight  for  several  days.  When  either  of  the  above  solutions  is 
boiled  with  sulphur,  the  solution  contains  calcium,  with  5  r«juiv.  of 
sulphur  —  the  qniiitosnlfihiirct  ofnilrium,  (Ca-f-5S.  101.) 

Phosphuret  of  Calcium  (Ca  -\-  P.  o(>.2)  is  formed  by  passing  the  vapor 
of  phosphorus  over  quick  lime,  at  a  low  red  heat.  It  is  a  brown  sub- 
stance, and,  when  thrown  into  water,  form*,  by  mutual  decomposition, 
phosphureted  hydrogen,  hypophosphorons  acid,  and  phosphoric  mid. 


Chloride  of  Lime.  Ca  +  O+  Cl.  63.92.  This  substance, 
commonly  called  oiymur'mtt'  of  limr,  or  bit  aching  powdn.  i> 
prepared  by  exposing  recently-slacked  lime  to  an  atmosphere 
of  chlorine.  The  gas  is  rapidly  absorbed,  and  enters  into 
direct  combination  with  the  lime,  although  Dr.  Ure  thinks 
that  no  definite  compound  is  formed. 

Properties.  A  dry,  white  powder,  similar  to  quick  lime, 
having  the  odor  of  chlorine,  which  it  readily  yields  up  when 
moistened  with  water;  possesses  powerful  bleaching  proper- 
ties, for  which  purpose  it  is  extensively  used  in  the  arts. 
The  strength  of  the  chloride  is  estimated  by  the  quantity  of 
indigo  which  a  given  portion  of  the  bleaching  solution  will 
deprive  of  its  color.  Used  also  in  medicine,  as  a  disinfecting 
agent ;  it  should  be  kept  in  every  family. 

MAGNESIUM.     Syrnb.  Mg.     Equiv.  12.7. 

Magjiesium  was  discovered  and  obtained  in  small  quantities 
by  Sir  H.  Davy,  by  means  of  galvanism  ;  but  M.  Bussy,  in 
1830,  obtained  it  in  greater  abundance  by  the  action  of  po- 
tassium on  chloride  of  magnesium. 

Process.  For  this  purpose,  five  or  six  pieces  of  potassium, 
of  the  size  of  peas,  were  introduced  into  a  glass  tube,  the 
sealed  extremity  of  which  was  bent  into  the  form  of  a  retort, 
and  upon  the  potassium  were  laid  fragments  of  chloride  of 
magnesium;  the  latter  being  then  heated  to  near  its  point  of 
fusion,  a  lamp  was  applied  to  the  potassium,  and  its  vapor 
transmitted  through  the  mass  of  the  heated  chloride.  Vivid 
incandescence  immediately  took  place;  and,  on  putting  the 
mass,  after  cooling,  into  water,  the  chloride  of  potassium,  with 
undecomposed  chloride  of  magnesium,  was  dissolved,  and 
metallic  magnesium  subsided.  —  T. 


Compounds  of  Magnesium.  233 

Properties.  A  very  malleable  solid,  of  a  white  color,  like 
silver,  and  of  a  brilliant,  metallic  lustre.  Dry,  air  and  water 
do  not  oxidize  it,  but  moist  air  does;  heated  to  redness  in 
oxygen  gas,  it  burns  vividly,  and  forms  magnesia.  In  chlo- 
rine gas  it  inflames  spontaneously. 

Compounds  of  Magnesium. 

Protoxide  of  Magnesium,  (Mg-J-O.  20.7,)  commonly  known 
by  the  name  of  magnesia,  is  prepared  by  exposing  the  car- 
bonate to  a  strong  heat,  to  expel  the  carbonic  acid. 

Properties.  A  white,  fusible  powder,  of  an  earthy  appear- 
ance, without  taste  or  odor;  sp.  gr.  2.3;  very  infusible,  and 
sparingly  soluble  in  water,  requiring  5142  times  its  weight 
at  (i9°,  and  36,000  of  boiling  water  to  dissolve  it.  The  prod- 
uct is  a  hydrate.  It  changes  vegetable  infusions  slightly, 
but  possesses  the  properties  of  an  alkali,  by  forming  neutral 
salts  with  acids;  absorbs  water  and  carbonic  acid  from  the 
air,  and  should  be  kept  in  close  bottles.  It  exists  in  nature 
in  serpentine,  steatite,  jnagnesite,  and  in  sea-water,  in  con- 
siderable abundance. 

Chloride  of  Magnesium  (Mg-f-Cl.  48.12)  is  prepared  by 
dissolving  magnesia  in  hydrochloric  acid,  evaporating  to  dry- 
ness,  mixing  the  resrdue  with  its  .own  weight  of  hydrochlorate 
of  ammonia,  and  projecting  the  mixture,  in  successive  portions, 
into  a  platinum  crucible,  at  a  red  heat.  The  ammonia  is 
expelled,  and  the  chloride  remains  a  transparent,  colorless 
mass ;  very  deliquescent,  and  soluble  in  water  and  alcohol. 

Iodide  of  Magnesium  (Mg-f-I.  139)  is  formed  by  dissolving  magnesia 
in  hydriodic  acid  ;  known  only  in  solution  with  water. 

Bromide  of  Magnesium  (Mg-f-Br.  91.1)  is  prepared  by  dissolving 
magnesia  in  hydrobromic  acid.  It  occurs  in  small  acicular  crystals, 
of  a  sharp  taste,  very  deliquescent  and  soluble  ;  it  is  decomposed  by  a 
strong  heat. 

Fluoride  of  Magnesium  (Mg  -f-  F.  31 .38)  is  formed  by  digesting  mag- 
nesia in  excess  of  hydrofluoric  acid ;  it  is  insoluble,  and  bears  a  red  heat 
without  decomposition. 

20* 


234  Metals.  —  Aluminium. 

SECT.  3.     METALLIC  BASES  OP  THE  EARTHS. 
ALUMIXWM.    Symb.  Al.    Equiv.  13.7. 

Sir  H.  Davy  proved  that  alumina  was  an  oxidized  body, 
and  Wohler  succeeded  in  decomposing  it,  from  which  he  ob- 
tained the  pure  metal,  aluminium. 

Process.  This  metal  may  be  obtained  by  heating  the 
chloride  of  aluminium  with  potassium  in  a  covered  platinum 
or  porcelain  crucible.  Intense  heat  is  evolved  during  the 
process.  After  cooling  the  mass,  it  is  put  into  water,  by 
which  the  saline  matter  is  dissolved ;  hydrogen  gas,  of 
an  offensive  odor,  is  evolved,  and  a  gray  powder  subsides. 
This  powder,  after  being  washed  in  cold  water,  is  pure 
(iliiininiuni, 

* 

Properties.  Aluminium,  as  thus  prepared,  is  a  gray  powder, 
similar  to  platinum,  but  when  rubbed  in  a  mortar,  exhibits 
distinctly  a  metallic  lustre.  Fuses  at  a  higher  temperature 
than  cast  iron,  and  in  this  state  is  a  conductor  of  electricity, 
but  a  non-conductor  when  cold. 

Ezp.  Heated  in  the  air  to  redness,  it  burns  brilliantly,  and  f<>rms 
alumina  ;  but  when  introduced  into  oxygen  gas,  at  a  rod  heat,  it  burns 
with  siHJh  splendor,  that  the  eye  can  hardly  support  the  light,  and  with 
so  much  heat,  that  the  resulting  alumina  is  partially  fused  into  yrlloxv 
fragments,  as  hard  as  corundum,  which  not  only  scratch,  but 
lutely  cut  glass. 

Exp,  Takes  fire  in  chlorine  gas  at  a  red  heat,  but  is  not  oxidizrd  hy 
water  at  common  temperatures,  nor  attacked  by  cold  sulphuric  .-m-l 
nitric  acids  ;  soluble  in  solutions  of  potassa  and  ammonia,  and  in  hot 
sulphuric,  or  dilute  sulphuric  and  hydrochloric  acids. 

Compounds  of  Aluminium. 

Sesquioxide  of  Aluminium  (2A1  -f-  3O.  27.4  +  24  =  51.4) 
is  the  only  known  oxide  of  aluminium,  and  is  commonly 
called  alumina,  or  aluminous  earth. 

Natural  History.  Alumina  is  very  abundant  in  nature, 
being  found  in  every  region  of  the  globe,  and  in  rocks  of  all 
ages ;  hence  it  is  one  of  the  principal  ingredients  in  most 
soils.  The  different  kinds  of  clay  of  which  bricks,  pipes,  and 
earthen-ware  are  made,  consist  mostly  of  hydrate  of  alumina. 


Compounds  of  Aluminium.  235 


It  is  also  found  beautifully  crystallized,  in  some  of  the  most 
beautiful  gems.  The  ruby  and  the  sapphire  are  nearly  pure 
alumina. 

Process.  It  may  be  prepared  for  chemical  purposes  from 
alum,  which  is  a  sulphate  of  alumina  and  pot  ass  a.  Dissolve 
pure  alum  in  water,  and  precipitate  the  alumina  by  carbonate 
of  ammonia.  THis,  when  washed  in  hot  water  and  filtered, 
is  the  hydrate,  which  may  be  rendered  pure  by  a  white  heat. 
An  easier  process  is  to  expose  the  sulphate  of  alumina  and 
ammonia  to  a  strong  heat,  so  as  to  expel  the  ammonia  and 
sulphuric  acid.  M.  Gaudin  has  succeeded  in  forming  rubies, 
by  mixing  ammoniacal  alum  with  -j^^  part  of  chromate  of 
potassa,  and  exposing  to  a  high  heat. 

Properties.  Inodorous,  tasteless,  and  possesses  the  proper- 
tics  both  of  an  acid  and  an  alkali ;  insoluble  in  water,  but  has 
a  powerful  affinity  for  it ;  when  moistened,  it  forms  a  ductile 
mass,  which  gives  it  its  great  utility  in  the  arts.  It  is  a  re- 
markable exception  to  the  law,  that  heat  expands  all  bodies. 
There  are  probably  several  hydrates  of  alumina. 

Uses.     Used  for  bricks,  and  various  kinds  of  pottery. 

ScsquicMoridc  of  Aluminium  (2A1  +  3C1.  133.66)  was  dis- 
covered by  Wohler,  by  transmitting  dry  chlorine  gas  over  a 
mixture  of  alumina  and  charcoal,  heated  to  redness.  It  is  of 
a  p:ile,  greenish-yellow  color,  partially  translucent,  of  a  highly 
crystalline,  lamellated  texture,  somewhat  like  talc,  but  with- 
out regular  crystals.  On  exposure  to  the  air,  it  fumes  slightly, 
emitting  an  odor,  like  hydrochloric  acid  gas. 

Exp.  When  thrown  into  water,  it  is  speedily  dissolved  with  a  hiss- 
ing noise,  and  so  much  heat  is  evolved,  that  the  water,  if  in  small 
quantities,  is  brought  into  a  state  of  brisk  ebullition,  and  forms  the 
hytlrochl  orate  of  alumina,. 

Scsquisulphuret  of.  Aluminium  (2A1-J-3S.  75.7)  is  prepared  by  drop- 
ing  a  piece  of  sulphur  on  to  aluminium,  strongly  heated.  It  is  a  vitri- 
fied, semi-metallic  substance,  of  a  dark  color. 

Scsquiphosphuret  of  Aluminium  (2Al-f-3P.  74.5)  is  formed  by  heat- 
ing aluminium  in  contact  with  the  vapor  of  phosphorus  ;  it  is  a  black- 
ish-gray, pulverulent  mass,  which,  by  friction,  acquires  a  dark  gray 
metallic  lustre,  and,  in  the  air,  has  the  odor  of  phosphureted  hy- 
drogen. 

Sesquiseleniuret  of  Aluminium  (2Al-{-3Se.  146.2)  is  obtained  by 
heating  to  redness  a  mixture  of  selenium  and  aluminium.  It  is  a 
black,  pulverulent  substance,  which  acquires  a  metallic  lustre  when 
rubbed. 


236  Metals.  —  Glucinium  —  Yttrium. 


GLUCINIUM.    Syrab.  G.    Equiv.  26.5.    Sp.  gr.  3. 

Glucinium  was  obtained  by  Wohler,  in  1828,  by  the  action 
of  potassium  upon  the  chloride  of  glucinium.  The  process  is 
similar  to  that  for  obtaining  aluminium.  It  appears  in  the 
form  of  a  gray  powder,  which  acquires  the  metallic  lustre  by 
burnishing,  and  is  easily  oxidized. 

Sesquioxide  of  Glucinium,  or  Glucina,  (2G-{-3O.  .77,) 
was  discovered  by  Vauquelin,  in  1798.  It  is  found  only  in 
the  minerals  emerald,  brryl,  and  cuclase. 

Process.  It  is  obtained  by  exposing  beryl  in  fine  powder, 
with  three  times  its  weight  of  carbonate  of  potassa,  to  a  strong 
red  heat.  The  fused  mass  is  dissolved  in  dilute  hydrochloric 
acid,  evaporated  to  dryness,  re-dissolved  in  acidulated  water. 
and  the  alumina  and  glucina  are  thrown  down  by  ammonia , 
the  precipitate  macerated  oy  carbonate  of  ammonia,  which 
dissolves  the  glucina,  and  on  boiling  the  filtered  liquor,  car- 
bonate of  glucina  subsides;  the  carbonic  aci'd  is  then  expelled 
by  a  red  heat. 

Properties.  A  white  powder,  without  taste  or  odor,  quite 
insoluble  in  water.  Pure  potassa  or  soda  precipitates  it  from 
its  salts;  distinguished  from  alumina  by  being  prrripit;itr«I 
from  its  solution  with  carbonate  of  ammonia,  when  the  solu- 
tion is  boiled. 

YTTRIUM.    Symb.  Y.     Equiv.  32.2. 

Yttrium  was  prepared  by  Wohler,  in  1828,  by  a  process 
similar  to  that  for  obtaining  glucinium. 

Properties.  It  has  a  scaly  texture,  a  grayish-black  color, 
and  a  perfectly  metallic  lustre.  It  is  a  brittle  metal,  and 
burns  with  splendor  in  common  air,  and  with  still  greater 
brilliancy  in  oxygen  gas.  The  result  of  this  combustion  is 
the  earth  yttria,  which  was  discovered  in  1794,  by  Gadolin, 
in  a  mineral  at  Ytterby,  Sweden.  It  is  of  a  white  color, 
soluble  in  sulphuric  acid,  and  combines  with  sulphur,  sele- 
nium, and  phosphorus.  Its  salts  have  a  sweetish  taste,  and 
some  of  them  have  an  amethystine  color. 


Thorium  —  Zirconium.  237 

THORIUM.     Symb.  Th.     Equiv.  59.6. 

This  metal  was  procured  by  the  action  of  potassium  on  the 
chloride  of  thorium ;  decomposition  being  accompanied  by  a 
slight  detonation.  On  washing  the  mass,  thorium  is  left,  in 
the  form  of  a  heavy,  metallic  powder,  of  a  deep  leaden-gray 
color  ;  and,  when  pressed  in  an  agate  mortar,  it  acquires 
metallic  lustre  and  an  iron-gray  tint. — T. 

Properties.  Thorium  is  not  easily  oxidized  at  common 
temperatures,  but  burns  with  great  brilliancy  in  the  air.  It 
is  not  acted  upon  by  alkalies,  scarcely  at  all  by  nitric,  and 
slowly  by  sulphuric  acid;  but  is  readily  dissolved  by  hydro- 
chloric acid,  with  the  disengagement  of  hydrogen  gas. 

Protoxide  of  Thorium,  or  Thorina,  (ThO.  67.6,)  was  dis- 
covered by  Berzelius,  in  1828,  in  a  rare  mineral  from  Nor- 
way, called  thorite.  It  is  a  white,  earthy  substance,  soluble 
in  none  of  the  acids,  except  the  sulphuric,  and  is  precipitated 
from  its  solutions  by  the  caustic  alkalies  as  a  hydrate,  in 
which  state  it  absorbs  carbonic  acid  from  the  atmosphere, 
and  dissolves  in  acids. 

It  is  distinguished  from  alumina  and  glucina,  by  its  insolu- 
bility in  pure  potassa,  and  from  yttria,  by  forming  with  sul- 
phate of  potassa  a  double  salt,  insoluble  in  a  cold,  saturated 
solution  of  sulphate  of  potassa. 


ZIRCONIUM.     Syrab.  Zr.     Equiv.  33.7.  t 

Zirconium  was  discovered  by  Berzelius,  in  1824. 

Process.  It  is  obtained  by  heating  the  double  fluoride  of 
zirconia  and  potassa,  carefully  dried  and  mixed  with  potassium, 
in  a  glass  or  iron  retort.  The  mass  is  then  washed  in  hot 
water,  and  digested  for  some  time  in  hydrochloric  acid. 

Properties.  This  substance  exists  in  the  form  of  a  black 
powder.  It  may  be  pressed  out  into  thin,  shining  scales,  but 
its  particles  adhere  very  slightly.  It  is  a  non-conductor  of 
electricity.  It  takes  fire,  when  heated  in  the  open  air,  at  a 
temperature  below  a  red  heat ;  the  product  is  zirconia. 

Scsquioxide  of  Zirconium,  or  Zirconia,  (2Zr-j-3O.  91.4,)  was  dis- 
covered by  Klaproth,  in  1789,  from  the  Zircon,  or  Jargon,  of  Ceylon. 


Metals.  —  Manganese. 

17  parts  of  this  substance,  finely  pulverized,  and  mixed  with  21  of 
litharge,  may  be  fused,  arid  a  glass  obtained,  soluble  in  acids,  from 
which  the  zirconia  is  derived ;  or  it  can  be  formed  directly  by  the  com- 
bustion  of  the  metal  in  oxygen  or  common  air. 

Properties.  A  fine,  white  powder,  inodorous  and  taste- 
less ;  sp.  gr.  4 ;  exposed  to  a  strong  heat,  it  fuses,  assuming  a 
light  gray  color ;  when  cool,  it  is  so  hard  as  to  strike  fin*  with 
steel,  and  to  scratch  quartz  crystal. 


ORDER  II.     METALS^THE  OXIDES  OF  WHICH  ARE  NEITHER 
ALKALIES  NOR  EARTHS. 

SECT.    1.     Metals  which  decompose  Water  at  a  red  Heat. 
MjUrGJVVESE.    Symb.  Mn.    Eq.  27.7.     Sp.  gr.  8.013. 

History.  In  1774,  Scheele  described  the  black  oxide  of 
manganese  as  "  a  peculiar  earth."  Gahn  'subsequently  dis- 
covered that  it  contained  a  new  metal,  to  which  he  gave  the 
name  of  magnesium,  a  term  applied  aflerwards  to  the  met. -ill i<- 
base  of  magnesia ;  and  for  which  the  words  mangancsium  and 
mangamum  have  been  substituted.  The  metal  is  not  found 
in  the  native  or  tin  combined  state,  but  its  oxides  are  very 
abundant. 

Process.  Make  a  paste  with  finely-pulverized  oxide  of 
manganese  and  oil,  and  expose  it  to  the  heat  of  a  smith's 
foFge,  in  a  Hessian  crucible,  lined  with  charcoal,  for  the 
space  of  two  hours. 

Properties.  A  hard,  brittle  metal,  of  a  grayish-rwhite  color, 
and  granular  texture;  very  infusible;  not  attracted  by  the  mag- 
net, except  when  it  contains  iron ;  soon  tarnishes  on  exposure 
to  the  air,  and  absorbs  oxygen  rapidly  when  heated  to  redness. 
Decomposes  water  slowly  at  common  temperatures,  but  rapidly 
at  a  red  heat. 

Compounds  of  Manganese. 

Protoiidt  of  Manganese  (Mn  +  O.  35.7)  may  be  formed, 
as  shown  by  Berthier,  by  exposing  the  peroxide,  sesquioxirle, 
or  red  oxide  of  manganese,  to  the  combined  agency  of  char- 


Compounds  of  Manganese.  239 

coal,  and  a  white  heat;  or  by  exposing  either  of  the  oxides, 
contained  in  a  glass  tube,  to  a  current  of  hydrogen  gas,  at  an 
elevated  temperature. 

Properties.  When  pure,  it  is  of  a  light  green,  or  moun- 
tain-green color,  undergoing  little  if  any  change  in  the  open 
air,  but  oxidizes  rapidly  at  600°  Fahr.,  and  is  instantly 
converted  into  the  red  oxide,  at  a  low  red  heat,  and  some- 
times takes  fire.  It  is  the  salifiable  base  of  the  metal,  and  is 
contained  in  all  its  salts;  hence  its  strong  affinity  for  acids. 

Sesquioxide  of  Manganese  (2Mn -f-3O,  or  Mn-f-liO.  79.4)  occurs 
nearly  pure  in  nature,  and  may  be  formed  by  exposing  the  peroxide  to 
a  red  heat.  It  is  the  chief  residue  of  the  usual  process  of  obtaining 
oxygen  gas,  but  it  is  difficult  to  regulate  the  heat  so  a,s  to  obtain  it  in  a 
pure  state. 

Properties.  The  color  is  brown  or  black,  according  to 
the  source  from  which  it  is  obtained ;  unites  with  nitric  and 
sulphuric  acids,  and  is  converted,  by  exposure  to  the  air,  into 
the  peroxide. 

Peroxide  of  Manganese.  Mn-|-2O.  43.7.  This  is  a  well- 
known  native  product,  commonly  called  black  oxide  of  man- 
ganese. 

Properties.  It  occurs  generally  in  masses,  of  an  earthy 
appearance,  and  black  color,  mixed  with  other  substances; 
but  it  is  frequently  found  in  small  prismatic  crystals.  It  is 
not  affected  by  exposure  to  the  air  or  water,  but  yields  oxy- 
gen when  heated  to  redness,  and  is  the  substance  most 
generally  employed  for  that  purpose,  (see  page  130 ;)  does 
not  unite  with  acids  or  alkalies. 

Uses.  Employed  in  the  arts  for  coloring  glass,  in  prepar- 
ing chlorine  gas,  and  in  forming  the  salts  of  manganese. 

Red  Oxide  of  Manganese.  3Mn  +  4O.  115.1.  This  is 
identical  with  the  oxidum  manganoso-manganium  of  Arfwed- 
son,  and  occurs  as  a  natural  product.  It  may  be  formed  arti- 
ficially by  exposing  the  peroxide  or  sesquioxide  to  a  white  heat. 

Properties.  Color,  when  finely  rubbed,  is  nearly  black 
when  warm,  and  brownish-red  when  cold.  It  is  permanent 
in  the  air  at  all  temperatures,  dissolves  in  small  quantities  by 
cold  sulphuric  acid,  and  more  rapidly  by  the  aid  of  chlorine ; 


240  Metals.  —  Manganese. 

the  solution  has  an  amethystine  tint.     It  is  the  cause  of  the 
rich  color  of  the  amethyst. 

VarticUe.  4Mn4-7O.  166.8.  Sp.  gr.  4.531.  Known  only  at  a 
natural  production,  and  first  noticed  by  Mr.  Phillips  among  some  ores 
of  manganese,  found  at  Hartshill  in  Warwickshire.  It  resembles  the 
peroxide  in  color,  for  which  it  was  first  mistaken,  but  may  be  distin- 
guished from  it  by  its  stronger  lustre,  greater  hardness,  more  lamel- 
lated  texture,  and  by  yielding  water  when  heated  to  redness.  It  i* 
probably,  like  the  red  oxide,  a  comoound  of  two  oxides,  consisting  of 
2  equivalents  of  the  peroxide,  and  1  of  the  sesquioxide  of  manganese, 
with  1  of  water.  — T. 

Manganic  Acid.  Mn+3O.  51.7.  When  peroxide  of 
manganese  is  mixed  with  equal  weights  of  nitre,  or  carbon- 
ate of  potassa,  and  heated  to  redness,  it  fuses,  and  a  gr«  n- 
colored  mass  is  formed,  known  by  the  name  of  mint  ml 
chameleon,  from  the  property  of  its  solution  to  pass  through 
several  shades  of  color. 

Exp.  On  the  addition  of  cold  water,  a  green  solution  is  formed, 
which  soon  becomes  blue,  ;,t<r;//r,  and  red',  and  ultimately  a  brown, 
fl.xjculent  matter  — hydrated  peroxide  of  manganese  —  subsides.  —  T. 

Theory.  These  changes  are  owing  to  the  formation  of 
manganate  of  potassa,  of  a  green  color,  which  pusses  to  the 
permanganate  of  potassa,  which  is  red,  the  blue  and  purple 
being  due  to  a  mixture  of  these  compounds;  but  the  man- 
ganic acid  has  not  been  obtained  in  a  separate  state,  owing 
to  its  ready  decomposition. 

Permanganic  Acid.  2Mn-f-7O.  111.4.  This  acid  if 
more  permanent,  though  easily  decomposed,  even  by  contact 
with  paper  or  linen  in  filtering.  It  may  be  obtained  from 
the  permanganate  of  baryta,  by  sulphuric  acid. 

Properties.  Color  red ;  decomposed  by  water  at  86° ;  col- 
oring matter  is  bleached  by  it,  but  particles  of  organic  matter 
floating  in  the  air  decompose  it  rapidly. 

ProtoclJorlde  of  Manganese  (Mn-f  Cl.  63.12)  is  prepared  by  evap- 
orating a  solution  of  the  chloride  to  dryness,  and  heating  it  to  n 
in  a  glass  tube,  while  a  current  of  hydrochloric  acid  gas  is  transmitted 
through  it ;  fuses  at  a  red  heat,  and  forms  a  pink-colored  laniellatnl 
mass  on  cooling  ;  deliquescent,  and  very  soluble  in  water.  —  T. 

Perchloride  of  Manganese  (2Mn-f  7C1.  303.34)  was  discovered  by 
Dumas,  and  formed  by  putting  a  solution  of  permanganic  into  sul- 
phuric acid,  and  adding  fused  sea-salt. 

Properties.  When  first  formed,  it  is  a  greenish-colored 
vapor  ;  but  by  passing  it  through  a  glass  tube  cooled  to  -5°, 


Iron.  24  \ 

it  condenses  into   a  greenish-brown  liquid,  decomposed  in- 
stantly by  water. 

Perfluoride  of  Manganese  (2Mn-J-7F.  18G.16)  was  discovered  by 
Dumas  and  Wb'hler.  Prepared  by  mixing  the  mineral  chameleon  with 
half  its  weight  of  fluor-spar  in  a  platinum  vessel,  and  decomposing  the 
mixture  with  fuming  sulphuric  acid. 

Properties.  A  yellowish-green  gas,  or  vapor,  which  ac- 
quires a  beautiful  purple-red  color  when  mixed  with  air ; 
freely  absorbed  by  water,  giving  to  the  solution  the  same  red 
tint;  acts  on  glass  with  the  formation  of  fluosilicic  acid  gas, 
and  the  deposition  of  a  brown  matter,  which  acquires  a  deep 
purple-red  tint  by  the  addition  of  water. 

Protosul/i/iuret  of  Manganese  (Mn-j-S.  43.8)  is  found  native  in 
Cornwall,  England,  and  may  be  formed  by  igniting  the  sulphate  with 
one  sixth  of  its  weight  of  charcoal,  in  powder. 

Cijiinuret  of  Manganese.     Mil  -f  Cy.  27.7  -f-  £0.39  —  54.09,  eqniv. 

Phos/thuret  and  Carburet  of  Manganese  may  be  obtained  by  heating 
the  metal  in  contact  with  phosphorus  or  carbon. 

Alloys  of  Manganese.  Manganese  unites  with  several  of 
the  metals,  forming  alloys  of  little  importance. 


/flO.V.     Symb.  Fe.     Equiv.  23.     Sp.  gr.  7.73. 

History.  Iron  is  decidedly  the  most  important  and  useful 
of  the  metals.  It  appears  essential  to  a  state  of  civilization  ; 
hence  it  is  the  most  abundant,  and  widely  diffused  throughout 
different  parts  of  the  earth.  Hence,  too,  it  seems  to  have 
been  made  known  to  the  first  inhabitants  of  the  earth,  and 
used  in  all  ages  where  men  have  emerged  even  to  the  state 
of  barbarians.  It  was  formerly  called  Mars. 

Natural  History.  Iron  is  rarely  found  pure  in  nature. 
Even  meteoric  iron  is  alloyed  with  cobalt  and  nickel ;  but  its 
oxides  are  very  abundant.  In  combination  with  oxygen  and 
sulphur,  it  is  so  widely  diffused,  that  few  minerals  can  be 
found  that  do  not  contain  traces  of  it.  It  enters  also  into 
plants  and  animals.  The  ores  of  iron  are  the  red  oxides, 
including  red  and  brown  hematite,  the  black  oxide,  or  mag- 
netic iron  ore,  and  the  carbonate  of  the  protoxide,  either  pure 
or  in  the  form  of  clay  iron  ore. 

Process.     The  extraction  of  the  iron  from  the  ores  is  ef- 
21 


•242  Metals.  —  Iron. 

fected  by  subjecting  them,  after  being  roasted  and  reduced  to 
a  coarse  powder,  to  the  action  of  charcoal,  lime,  and  caloric; 
this  is  the  cast  iron,  which  contains  some  impurities,  es- 
pecially carbon.  The  malleable  or  wrought  iron  is  prepared 
from  this,  by  continuing  the  process  until  the  carbonaceous 
matter  is  burned  out ;  it  then  becomes  solid  again,  and  is 
put  under  a  roller  or  hammer  and  drawn  out  into  bars. 
Steel  is  the  wrought  iron  combined  with  carbon.  The  best 
wrought-iron  bars  are  surrounded  by  dry  charcoal  and  heated 
to  a  high  temperature. 

Properties.  Iron  has  a  peculiar  gray  color,  and  strong 
metallic  lustre,  which  is  brightened  by  polishing,  of  which  it 
is  capable  of  receiving  a  higher  degree  than  any  other  metal. 
It  is  less  ductile  and  malleable  than  some  others,  but  the  nm-t 
tenacious  of  all;  hence  it  may  be  drawn  out  into  fine  win-, 
but  not  into  thin  leaves.  Its  texture  is  fibrous,  and  when 
heated,  is  soft,  and  possesses  the  property  of  being  welded  to 
other  heated  iron.  When  cooled  suddenly,  it  is  brittle,  but 
may  be  rendered  malleable  again  by  heat;  it  is  very  infusible, 
and  when  combined  with  carbon,  very  hard.  In  this  state, 
it  is  capable  of  being  made  permanently  magnetic:  it  is  the 
great  repository  of  natural  magnets,  and  the  only  substance, 
save  cobalt  and  nickel,  which  possesses  magnetic  properties. 

Its  uses  in  the  arts  are  well  known. 


Compounds  of  Iron. 

Protoxide  of  Iron.  Fe  +  O.  36.  The  existence  of  this  ox- 
ide was  first  inferred  by  Gay  Lussac;  but  Stromeyer  obtained 
it  in  an  insulated  form,  by  transmitting  dry  hydrogen  gas 
over  the  protoxide  at  a  low  temperature.  It  may  also  be 
precipitated  from  its  salts  as  a  white  hydrate  by  pure  alkalies, 
as  a  carburet  by  alkaline  carbonates,  as  a  white  ferrocyanuret 
by  ferrocyanuret  of  potassium,  and  as  a  protosulphuret  by 
alkaline  hydrosulphates. 

Properties.  Color  dark  blue,  and  communicates  a  blue 
tint  to  substances  melted  with-  it.  It  is  magnetic,  and  so 
combustible,  that  it  takes  fire  spontaneously  in  the  open  air, 
and  is  converted  into  the  peroxide.  Its  salts  absorb  oxygen 
so  rapidly  from  the  air,  as  to  be  useful  in  eudiometry.  It  is 


Compounds  of  Iron.  243 

the  base  of  the  native  carbonate,  and  the  green  vitriol  of 
commerce." 

Peroxide  of  Iron.  2Fe-|-3O  or  Fe  +  1  JO.  80.  This  is  the 
red  hematite,  of  mineralogists,  a  very  abundant  natural  pro- 
duction. 

Proc-fss.  It  is  made  chemically  by  dissolving  iron  in  nitro- 
hydrochloric  acid,  and  adding  an  alkali. 

The  precipitate  is  of  a  brownish  color,  and  is  identical  with 
the  mineral  called  brown  hematite,  and  consists  of  1  equiv- 
alent of  the  peroxide  aird  2  of  water. 

Properties.  It  is  a  brownish-red  compound,  not  attracted 
by  the  magnet.  It  is  precipitated  from  its  salts  by  the  pure 
alkalies.  With  ferrocyanuret  of  potassium  it  forms  Prussian 
blue  ;  with  infusion  of  nutgalls  it  forms  ink. 

Tests  of  the  presence  of  iron  in  any  composition,  may  be  made  by 
boiling  it  with  nitric  acid,  which  converts  the  iron  into  the  peroxide  ; 
the  ferrocyanuret  of  potassium  will  then  form  a  blue  precipitate. 


Black  Oxide.  (Fe  +  O)  +  (2Fe-f-3O.)  116.  This  com- 
pound is  called,  by  Berzelius,  oxidum  fcrroso-ferricum,  and 
is  supposed  to  be  a  mixture  or  combination  of  the  two  pre- 
ceding oxides. 

It  occurs  native,  often  in  regylar  octohedral  crystals.  It 
is  formed  also  when  iron  is  heated  in  the  open  air,  or  in  con- 
tact with  moisture.  It  is  not  only  magnetic,  but  is  itself 
often  a  magnet.  With  sulphuric  acid,  an  olive-colored  so- 
lution is  formed,  containing  two  salts,  the  sulphate  of  the 
protoxide,  and  peroxide,  which  may  be  separated  from  each 
other  by  means  of  alcohol.  The  black  oxide  is  the  cause 
of  the  green  color  of  glass. 

ProtochJoride  of  Iron  (Fe  -f-  Cl.  63.42)  is  formed  by  dissolving  iron 
in  hydrochloric  acid,  evaporating  to  dryness,  and  heating  the  product 
to  redness,  in  a  tube  deprived  of  air.  It  is  a  gray,  crystalline  substance, 
fusing  at  a  red  heat,  and  is  easily  converted  into  the  hydrochlorate  of 
the  protoxide  of  iron. 

Perchloridc  of  Iron.  (2Fe  -f-  3d.  162.26)  is  formed  by  the  combustion 
of  iron  in  chlorine  gas.  It  is  a  yellowish-brown  substance,  crystal- 
lizes in  Small  iridescent  plates,  of  a  red  color  ;  volatilizes  at  little  a.bove 
212";  deliquesces  readily,  and  dissolves  in  water,  alcohol,  and  ether, 
and  is  converted  by  water  into  the  hydrochlorate  of  the  peroxide  of 
iron. 

Proticdide  of  Iron  (Fe-|-I.  154.3)  is  prepared  by  digest- 


244  Metals.  —  Iron. 

ing  iodine  in  water  and  iron  wire.  On  evaporating  the  solu- 
tion to  dryness,  without  exposure  to  the  air,  and  heating  it 
moderately,  it  yields  crystals  of  an  iron-gray  color  and  metal- 
lic lustre,  deliquescent,  very  soluble  in  water  and  alcohol, 
and  used  in  medicine  as  a  tonic. 

Tfie  Periodide  of  Iron  (2F-f  31.  434.9)  is  obtained  by  exposing  a  so- 
lution of  the  protiodide  to  the  air.  It  is  a  volatile,  red  compound,  .-<>lu- 
ble  in  water  and  alcohol. 

T/te  Prutobromide  of  Iron  (Fe-|-Br.    106.4)   and  the  Perbrmnide  of 
Iron  (HFe  -f-3Br.  201 .2)  are  formed  in  a  similar  manner  \\  itli  tin-  i 
and  IMV<-  similar  properties.     Protujflunritlt  of  Iron.    Fe  -f  F.  4t'.  > 

Ptrfiuoride  of  Iron  (2Fe -J- 3F.  112.04)  is  formed  by  dissolving  JMT- 
oxide  of  iron  in  hydrofluoric  acid.  As  the  acid  becomes  saturated, 
crystals  are  formed  in  small,  white,  square  tables,  which  are  sparingly 
soluble  in  water. 


Protosulphurct  of  Iron  (Fe  +  S.  44.1)  is  prepared  by 
heating  equal  parts  of  sulphur  and  iron-filings  in  a  covered 
Hessian  crucible;  considerable  heat  is  evolved,  and  a  yel- 
lowish-gray substance  is  formed  ;  this  is  completely  dissolved, 
if  pure,  by  dilute  sulphuric  acid,  yielding  hydrosulphuric 
acid.  It  exists  in  natilre,  in  the  variegated  copjxr  />i/r/( r.>, 
and  forms  a  black  precipitate,  when  hydrosulphate  of  ammo- 
nia is  mixed  with  the  sulphate  of  the  protoxide  of  iron. 

Sesquisulphuret  of  Iron  (2Fe4-  3S.  104.3)  is  formed  by  the  action  of 
the  hydrosulphuric  acid  on  the  hydrated  peroxide  of  iron. 

It  has  a  yellowish-gray  color,  and  dissolves  in  dilute  sul- 
phuric and  hydrochloric  acids,  with  the  formation  of  hydro- 
sulphuric  acid  and  bisulphuret  of  iron. 

Bisulphurct  of  Iron.  Fe  +  2S.  60.2.  This  is  the  iron 
pyrites  of  mineralogists,  and  occurs  abundantly  in  cubes,  or 
in  some  analogous  form,  of  a  yellow  color,  and  metallic  lus- 
tre ;  sp.  gr.  4.981  ;  so  hard  as  to  strike  fire  with  steel  ;  hence 
its  name. 

It  is  dissolved  by  nitrohydrochloric  acid,  but  by  no  other 
acid,  except  the  nitric.  By  heat,  it  is  converted  into  magnet- 
ic iron  pyrites,  if  in  close  vessels,  but  exposed  to  the  air,  into 
the  peroxide  of  iron. 

Magnetic  Iron  Pyrites.  (5Fe  +  S)  +  (Fe+2S.)  280.7. 
This  natural  product  appears  to  be  composed  of  5  equivs. 
of  the  protosulphuret  and  1  of  the  bisulphuret.  It  may 
be  formed  as  above.  It  is  much  more  easily  oxidized  than 
the  bisulphuret. 

Tetrasn'phure,t  of  Iron  (4Fe  -}-S.  128.1)  and  the  Disulphuret  of  Iron 
(2Fe  -|-  S.  .72)  may  be  formed  by  passing  hydrogen  gas,  at  a  red  heat, 
«ver  the  anhydrous  sulphate  of  the  protoxide  of  iron,  to  obtain  the  di- 


Compounds  of  Iron.  245 

sulphuret,  and  over  the  disulphate  of  the  peroxide  of  iron,  for  the  tetra- 
sulphuret. 

Properties.  They  exist  in  a  grayish-black  powder,  soluble 
in  dilute  sulphuric  acid,  with  the  evolution  of  hydrogen  and 
hydrofluoric  acid  gases. 


of  Iron   (2Fe-{-P.  71.7)  is   prepared  by  heating   the 
phusphuret  in  a  covered  crucible,  lined  with  charcoal. 

Properties.  It  is  a  fused,  granular  substance,  which  re- 
sembles iron  in  color  and  lustre,  but  is  very  brittle,  and  ren- 
ders iron  brittle,  when  contained  in  it,  as  it  sometimes  is. 

Pcrphosjiliiirrt.  of  Iron  (3Fe-j-4P.  140.8)  is  obtained  by  the  action  of 
phosphureted  hydrogen  on  sulphuret  of  iron,  and  resembles  the  pre- 
ceding in  most  of  its  properties. 

Carburets  of  Iron.  Carbon  and  iron  unite  in  several  pro- 
portions; only  three  seem  worthy  of  notice  —  graphite,  cast 
or  pig  iron,  and  steel. 

Graphite  is  known  as  a  natural  product,  under  the  names 
of  pi  iimb  ago  and  black-lead.  There  is  not  more  than  10  per 
cent,  of  iron,  and  often  not  5.  Used  for  pencils,  crayons, 
crucibles,  and  for  burnishing  iron. 

Cast  Iron  is  a  compound  of  carbon  and  iron,  and  is  the 
product  of  melting  the  ores  of  iron  with  charcoal.  Its  uses 
are  well  known. 

Steel  is  formed  by  filling  a  furnace  with  bars  of  the  best 
malleable  iron,  with  layers  of  charcoal  between,  and  subject- 
ing them  to  strong  heat  away  from  the  air  ;  about  1.3  to  1.75 
per  cent,  of  carbon  combines  with  the  iron.  This  is  the 
substance  used  for  the  various  purposes  of  the  arts.  It  is 
much  harder  than  iron,  but  more  brittle,  also  less  ductile  and 
malleable,  but  more  firm  in  its  texture,  and  capable  of  a 
higher  polish.  By  fusion  it  forms  cast  steel. 

Protocyannret  of  Iron  (Fe  -f-  Cy.  54.39)  is  prepared  by  mixing  in 
solution  cyanuret  of  potassium  with  sulphate  of  protoxide  of  iron;  on 
exposure  to  the  air,  it  passes  to  Prussian  blue, 

Protosulphocyanurct  of  Iron  (Fe  -f-  CyS2.  86.59)  is  obtained  by  dis- 
solving iron  in  hydrosulphocyanuric  acid,  and  evaporating  the  pale 
green  solution  to  dryness  in  vacua. 

Sequisulphocyanuret  of  Iron  (2Fe  -f-  3CyS*.  231.77)  is  prepared  by 
mixing  the  sulphocyanuret  of  potassium  with  any  salt  of  the  peroxide 
of  iron*.  It  has  a  blood-red  color,  and  is  a  very  delicate  test  of  the 
presence  of  iron. 

21* 


246  Metals  —Zinc 


Z/wYC.    Symb.  Zn.    Equiv.  32.3.    Sp.  gr.  7.00. 

Zinc  has  long  been  known  in  the  East,  India  and  China, 
but  was  first  distinctly  noticed  in  the  sixteenth  century,  by 
Paracelsus,  under  the  name  of  zinetum.  Henckel  is  the  first 
who  obtained  the  metal  from  calaminc,  in  the  year  1701 
Von  Swab  first  obtained  it  by  distillation  in  1742;  and  Mar- 
graff  published  a  process  in  the  Berlin  Memoirs  in  1"4<>. 

Natural  History.  Zinc,  like  most  of  the  metals,  is  rarely 
found  pure  in  nature,  but  is  an  abundant  substance  in  com- 
bination with  oxygen,  carbon,  and  sulphur. 

Process.  Commercial  zinc,  or  spelter,  is  generally  ob- 
tained from  calaminc,  native  carbonate  of  zinc,  or  from  the 
native  salphuret,  called  by  mineralogists  zinc  hit  ml,.  This 
is  oxidized  by  heating  it  in  the  open  air,  called  roasting.  It 
is  then  distilled ;  that  is,  it  is  heated  in  a  crucible  open  at 
the  bottom  and  closed  at  the  top,  to  which  is  affixed  a  mix-, 
which  terminates  just  above  a  basiu  of  water  ;  the  gaseous 
products,  with  the  vapor  of  zinc,  pass  through  the  tubr,  and 
the  zinc  is  condensed.  The  first  portions  are  impure,  con- 
taining cadmium  and  arsenic,  which  give  the  brown  blaze  ; 
when  the  blue  blaze  is  seen,  the  zinc  is  collected.  It  con- 
tains now  some  impurities,  which  are  removed  by  a  white 
heat  in  an  earthen  retort,  to  which  a  receiver  full  of  wai 
adapted. 

Properties.  This  metal  is  bluish-white,  with  a  strong 
metallic  lustre  and  lamellated  texture.  It  is  a  hard  and  brittle 
metal;  but  between  the  temperatures  of  210°  and  300°  Fahr., 
it  is  malleable  and  ductile,  and  in  this  state  is  rolled  out  into 
plates;  fuses  at  773°  Fahr.,  and  when  slowly  cooled,  crystal- 
lizes in  four  or  six-sided  prisms.  It  is  easily  pulverized 
when  heated  to  a  certain  temperature  below  redness,  and 
sublimes  at  a  high  temperature  in  close  vessels,  without 
change. 

Uses.  Zinc  is  used  extensively  in  the  arts,  for  the  construction  of 
voltaic  instruments,  and  for  covering  buildings.  It  has  been  pro- 
posed to  use  it  for  culinary  vessels,  water-pipes,  and  sheathing  for 
ships;  but  it  is  so  easily  oxidized  and  acted  upon  by  the  weakest 
acids,  that  it  is  unfit  for  these  uses. 


Compounds  of  Zinc.  247 

Compounds  of  Zinc. 

Protoxide  of  Zinc.  Zn  +  O.  49.3.  This  is  the  only  known 
oxide  of  zinc,  formerly  called  fowers  of  zinc ,  nihil  album, 
and  philosopher's  wooL 

Process.  It  is  obtained  by  the  combustion  of  zinc  in  the 
open  air,  in  oxygen  gas,  or  by  heating  Jthe  carbonate  to  red- 
IKISS.  It  is  found  native  in  Franklin,  New  Jersey. 

EX/I  Melt  zinc  in  a  covered  crucible,  and  when  it  is  at  a  white 
heal,  rouiove  the  cover;  it  will  burst  out  into  a  white  flame,  forming 
tin*  o.xide. 

The  Hydrated  Oxide  of  Zinc  may  "be  obtained  by  uniting 
a  rod  of  iron  and  zinc,  and  placing  them  in  caustic  ammonia, 
i(i  a  close  vessel.  ^  *'':]  ' 

Properties.  At  common  temperatures  it  is  white,  but  as- 
sumes a  yellow  color  when  heated  to  redness ;  insoluble  in 
water,  and  is  a  strong  salifiable  base. 

The  oxide  is  precipitated  from  its  solutions,  as  a  ivhiteliy- 
dratc,  by  pure  potassium  and  ammonia,  and  as  a  carbonate 
by  alkaline  carbonates.  The  oxide  is  sometimes  substituted 
for  white  lead  for  paint;  it  is  more  durable,  but  not  so  white. 

Berzelius  describes  a  suboxide,  and  Thenard  a  binoxide, 
but  they  are  doubtful  substances. 

Chloride  of  Zinc  (Zn  -(- Cl.  67.72)  is  formed  by  burning  zinc-filings 
in  chlorine.  It  is  colorless,  fusible  a  little  above  212°,  and  has  so  soft 
a  consistency  at  common  temperatures,  as  to  be  called  butter  of  zinc. 

Iodide  of  Zinc  (Zn  -{-  I-  158.6)  is  prepared  by  digesting  iodine  in 
water  with  zinc-nhngs. 

Bromide  of  Zinc  (Zn  -f-  Br.  110.7)  is  formed  in  a  similar  manner 
with  the  preceding. 

Fluoride  of  Zinc  (Zn  -f-F.  50.98)  is  prepared  by  the  action  of  hydro- 
fluoric acid  on  the  oxide  of  zinc.  It  exists  as  a  white  solid. 

Sulphuret  of  Zinc  (Zn-j-S.  48.4)  is  a  native  product, 
known  by  the  name  of  zinc  blende.  It  may  be  formed  by 
heating  sulphur  with  the  oxide;  it  crystallizes  in  dodeca- 
hedrons; lamellated  structure  ;  adamantine  lustre;  color  red, 
yellow,  brown,  or  black.  Cyanuret  of  Zinc  ZnCy.  58.69. 

CADMIUM.     Symb.  Cd.   Equiv.  55.8.    Sp.  gr.  8.604. 

History.  Cadmium  was  discovered  in  1817,  by  Stromeyer, 
of  Gottingen,  in  an  oxide  of  zinc  which  had  been  prepared 


248  Metals.  —  Cadmium. 

ror  medical  use.  Dr.  Clark  detected  it  in  the  zinc  ores  of 
Derbyshire,  and  in  the  common  zinc  of  commerce,  and 
Mr.  Herapath  found  it  in  considerable  quantities  in  the  zinc 
works  near  Bristol,  England. 

Process.  The  following  is  the  process  of  Stromeycr : 
The  ore  of  cadmium  is  dissolved  in  hydrochloric  or  sulphuric 
acid  in  excess.  The  sulphuret  of  cadmium  is  precipitated 
by  hydrosulphuric  acid.  Nitric  acid  decomposes  tins,  and 
forms  a  nitrate,  which  is  evaporated  to  dryness.  To  a  solu- 
tion of  this  in  water,  an  excess  of  carbonate  of  ammonia  is 
added,  and  the  white  carbonate  of  the  oxide  of  cadmium  is 
precipitated,  which,  when  subjected  to  a  red  heat,  yields  a 
pure  oxide.  The  metallic  cadmium  is  obtained  from  the  ox- 
ide, by  heating  it  with  charcoal. 

Properties.  Cadmium  resembles  tin  in  its  color  and  lus- 
tre, but  is  harder  and  more  tenacious;  very  ductile  and 
malleable;  melts  at  about  the  same  temperature  as  tin,  ;md 
is  nearly  as  volatile  as  mercury.  Heated  in  the  open  air,  it 
absorbs  oxygen,  and  is  converted  into  the 

Oxide  of  Cadmium,  (Cd  +  O.  63.8,)  which  is  the  only 
known  oxide ;  is  a  strong  alkaline  base,  forming  neutral  >a!i> 
with  acids;  insoluble  in  water;  fixed  in  the  fire;  and  pre- 
cipitated by  all  the  alkaline  carbonates,  and  by  pure  ammonia 
and  potassa. 

Chloride  of  Cadmium.  Cd-fCl.  91.22.  This  compound 
is  formed  by  dissolving  oxide  of  cadmium  in  hydrochloric 
acid.  By  concentration,  the  chloride  crystallizes  in  four- 
sided  rectangular  prisms,  which  lose  their  water  of  crystal- 
lization by  he*j,  and  even  in  dry  air ;  fused  below  redness, 
and  sublimes  at  a  high  temperature. 

Iodide  of  Cadmium  (Cd-f-I.  182.1)  is  formed  in  the  same  way  as 
the  iodide  of  zinc  ;  soluble  in  water  and  alcohol,  and  crystallizes  in 
large,  colorless,  transparent,  hexagonal  tables,  which  do  not  change  in 
the  air,  and  have  a  pearly  lustre.  By  heat  they  lose  water,  and  then 
fuse. 

Sulphuret  of  Cadmium  (Cd-j-S.  71.9)  occurs  in  nature  in 
zinc  blende,  and  is  prepared  by  the  action  of  hydrosnlphuric 
acid  on  the  salts  of  cadmium.  It  has  a  yellowish-orange 
color,  and  may  be  distinguished  from  the  sulphuret  of  arsenic 
by  being  insoluble  in  pure  potassa,  and  by  sustaining  a  white 
heat  without  subliming. 


Tin.  249 

of    Cadmium   is   a  gray   compound,   very   brittle    and 
fusible. 


T/JV.    Symb.  Sn.     Equiv.  57.9.     Sp.  gr.  7.2. 

Tin  was  known  to  the  ancients,  in  the  time  of  Moses; 
siid  was  obtained,  chiefly  from  Cornwall,  England,  and  Spain, 
at  a  very  early  period,  by  the  Phoenicians. 

Proffsss.  The  tin  of  commerce  is  obtained  from  the 
native  oxide  by  heat  and  charcoal,  and*  in  the  form  of  block 
an<1  i^rain  tin. 

Stream  Tin  is  the  native  oxide  of  Cornwall,  which  is 
found  in  rounded  pebbles,  occasioned  by  the  action  of  water. 
Tin  is  seldom  perfectly  pure,  containing  a  little  copper,  iron, 
and  arsenic.  That  from  Malacca  is  the  purest. 

Tin  Foil  is  often  an  alloy  of  tin  and  lead.  Block  tin  is 
less  pure  than  grain  tin. 

Properties.  Tin  has  a  color  and  lustre  resembling  silver. 
It  is  very  malleable.  Tin  foil  does  not  exceed  TjVtf  of  an 
kich  in  thickness,  but  its  ductility  and  tenacity  are  inferior  to 
many  of  the  metals.  When  bent  backward  and  forward,  a 
crackling  noise  is  produced,  by  which  it  may  be  readily  dis- 
tinguished from  lead,  zinc,  etc.  It  fuses  at  240°  Fahr,  When 
heated  to  whiteness,  it  takes  fire.  If  a  drop  of  the  fused  tin 
fall  upon  a  board,  it  will  divide  into  several  globules,  and 
burn  with  a  beautiful  white  light.  The  brilliancy  of  its  sur- 
face tarnishes  slowly  when  exposed  to  the  air  at  common 
temperatures,  but  oxidizes  at  a  high  temperature. 

Compounds  of  Ti?t. 

Protoxide  of  Tin  (Sn  +  O.  65.9.  sp.  gr.  6.666)  is  formed 
by  fusing  tin  for  some  time  in  an  open  vessel,  or  it  may  be 
precipitated,  as  a  hydrated  oxide,  from  a  solution  of  chloride 
of  tin,  by  an  alkaline  carbonate. 

Properties.  It  is  a  gray  powder,  permanent  in  the  air, 
unless  touched  by  a  red-hot  body,  when  it  takes  fire,  and  is 
converted  into  the  peroxide.  It  is  dissolved  in  the  strong 
«cids,  and  the  pure,  fixed  alkalies.  It  readily  absorbs  oxygen 
from  the  air  and  other  compounds;  hence  it  throws  down 


250  Metals.— Tin. 

mercury,  silver,  and  platinum,  from  their  salts.  With  gold, 
it  causes  the  purple  precipitate  of  Cassius  ;  by  this  charac- 
ter it  is  readily  distinguished.  It  is  precipitated  from  its 
solutions  by  hydrosulphuric  acid  as  a  black  protosulphuret. 

Scsquioride  nf  Tin  (2Sn  -f  3O.  130.*)  is  prepared  by  mixing  recentl y- 
precipitated  and  moist  hydratcd  peroxide  of  iron  with  a  solution  of 
protochloride  of  tin.  The  sesqttioxkle  is  precipitated  in  a  slimy,  gray 
mailer,  of  a  yellowish  tint,  from  oxide  of  iron ;  distinguished  from  the 
protoxide  by  being  soluble  in  ammonia. 

Binoxide  of  Tin  (8*  -|-2O.  ?:l.9)  is  prepared  by  tho  action 
of  nitric  acid  on  metallic  tin.  The  concentrated  arid  dors 
not  act  on  the  tin,  but,  on  the  addition  of  water,  violent  effer- 
vescence takes  place,  and  a  white  powder  —  the  hv«!r  it.-d  l>i- 
noxideof  tin  —  is  formed.  The  water  is  expelled  by  ln-at,  and 
the  pure  binoxide,  of  a  straw-yellow  color,  results.  The  hy- 
drated  oxide  may  also  be  precipitated  from  the  protochlond<> 
by  potassa,  ammonia,  or  the  alkaline  carbonates;  but  the 
properties  differ  from  that  formed  in  the  other  way,  the  latter 
being  dissolved  in  the  strong  acids,  while  the  former  is  not. 
It  acts  the  part  of  a  feeble  acid,  uniting  with  the  pure  alka- 
lies, and  forming  a  clnss  of  compounds — the  stnnmit' .-. 

Binoxide  of  tin  is  recognized  by  its  being  precipitated 
from  its  solutions  by  hydrochloric  acids  as  a  bulky  hydrate, 
and  by  any  of  the  alkalies  or  alkaline  carbonates.  When 
melted  with  glass,  it  forms  a  white  enamel. 

Protochloride  of  Tin  fSn-f  Cl.  93.3*2)  is  obtained  by  distilling  r^ua! 
weights  of  tin  and  bichloride  of  mercury.  It  is  a  gray  s  >h'l,  ot  r  •» 
ous  lustre  ;  fuses  below  redness,  and  sublimes  at  A  high  :• 
crystallizes  in  small,  white  needles.  A  solution  of  the  j>r,t.  .-;,!  ,i id" 
may  be  prepared  for  deoxidizing  purposes,  by  heating  granuhitril  tin 
in  strong  hydrochloric  acid,  as  long  as  hydrogen  gas  is  evolved. 

Bichloride  of  Tin  (Sn4-2Cl.   126.74)  is  formed  by  distilling  •- 
of  granulated  tin  with  24  of  bichloride  of  mercury,  or  by  heating  the 
protochloride  in  chlorine  gas. 

Properties.  It  is  a  colorless  liquid,  very  volatile,  yielding 
white  fumes  in  an  open  vessel ;  hence  formerly  called  the 
fuming  liquor  of  Libavius ;  boils  at  248° ;  sp.  gr.  of  its 
vapor,  9.1997;  mixed  with  ^  of  its  weight  of  water,  it  forms 
a  solid  hydrate,  but  dissolves  in  a  larger  quantity  of  water. 

Uses.  The  solution  called  ptrmuriate  of  tin  is  used  in  dyeing,  and 
is  prepared  by  dissolving  tin  in  nitrohydrochloric  acid. 

Protiodide  of  Tin  (Sn  -j-  I.  184.2)  is  prepared  by  heating  gran 
tin  with  2£  times  its  weight  of  iodine.     It  is  a  brownish-red  substance, 
very  fusible,  volatile,  and  soluble. 

Biniodide  of  Tin  (Sn-f2I.  3105)  is  prepared  by  dissolving  the  hy- 


Cobalt.  251 

drate  of  the  peroxide,  precipitated  by  alkalies,  from  the  bichloride,  in 
hydriodic  acid.  .  It  forms  yellow  crystals  of  a  silky  lustre. 

Proto sulphur e.t  of  Tin  (Sn-}-S.  74)  is  prepared  by  pouring  melted 
tin  upon  its  own  weight  of  sulphur,  and  stirring  rapidly  with 'a  stick. 
It  has  a  bluish-gray,  or  nearly  black  color,  and  metallic  lustre  ;  fuses 
at  red  heat,  and  has  a  lamellated  texture  when  cool. 

Scsqwsulphuret  of  Tin  (2  Sn-|-3S.  164.1)  rs  obtained  by  heating  to 
low  redness  the  protosulphuret  with  J  of  its  weight  of  sulphur,  ft  is 
a  deep  grayish-yellow  compound. 

Bisulpkuret  of  Tin.  Sn-j-2S.  90.1.  This  compound  wos  formerly 
called  Mosaic  gold,  and  may  be  prepared  by  heating  a  mixture  of  2 
parts  of  peroxide  of  tin,  2  of  sulphur,  and  1  part  of  hydrochlorate 
of  ammonia,  in  a  glass  or  earthen  retort,  to  a  low  red  heat,  till  sulphur- 
ous acid  ceases  to  be  evolved. 

Properties.  It  occurs  in  crystalline  scales,  of  a  golderi- 
yollow  color,  and  metallic  lustre  ;  soluble  in  pure  potassa, 
and  its  only  solvent  among  the  acids  is  the  nitrohydrochlo- 
ric  acid.  It  is  obtained,  as  a  hydrate,  by  the  action  of  hy- 
drosulphuric  acid,  and  the  bichloride  of  tin,  in  solution. 

Terphosphuret  of  7Yn(Sn-|-3P.  105)  is  formed,  according  to  Rose, 
by  the  action  of  phosphureted  hydrogen  on  a  solution  of  protochlo- 
ride  of  tin.  It  oxidizes  rapidly  in  the  air. 


COBALT.    Symb.  Co.     Equiv.  29.5.     Sp.  gr.  7.834. 

Cobalt  was  discovered  by  Brandt,  and  derives  its  name, 
Kobold,  an  evil  spirit,  from  the  belief  of  the  German  miners 
that  its  presence  was  unfavorable  to  that  of  valuable  metals. 

Natural  History.  It  exists  in  nature,  generally,  in  com- 
bination with  arsenic.  It  is  also  a  constant  ingredient  in 
meteoric  iron,  and  is  found  combined  with  sulphur  and  other 
combustibles. 

Process.  It  may  be  obtained  from  the  oxide,  by  heating 
it  in  connection  with  charcoal,  and  then  passing  over  it  a 
stream  of  hydrogen  gas,  to  combine  with  the  oxygen. 

Properties.  Cobalt  is  a  brittle  solid,  of  a  reddish-gray 
color,  and  weak  metallic  lustre;  fuses  at  130°  Wedgwood, 
and  crystallizes  when  slowly  cooled.  It  is  attracted  by  the 
magnet,  and  is  susceptible  of  being  rendered  permanently 
magnetic ;  absorbs  oxygen  when  heated  in  open  vessels.  It 
is  also  oxidized  by  nitric  acid,  and  decomposes  water  at  a 
red  heat. 


252  Met  0/5.  —  Cobalt. 


Compounds  of  Cobalt. 

Protoxide  of  Cobalt  (Co  +  O.  37.5)  is  obtained  by  de- 
composing the  carbonate,  by  heat,  in  a  vessel  from  which  the 
air  is  excluded. 

'  Properties.  It  has  an  ash-gray  color,  and  is  the  base  of 
all  the  salts  of  the  metal,  most  of  which  are  a  pink-blur. 
When  heated,  it  absorbs  oxygen,  and  is  converted  into  the 
peroxide.  It  is  distinguished  by  giving  a  blue  tint  to  borax 
when  melted  with  it 

Zaffre  is  an  impure  oxide  of  cobalt,  obtained  by  hentinir 
the  arseniuret  in  a  reverberatory  furnace.  When  this  sub- 
stance is  heated  with  sand  and  potassa,  a  beautiful  111  in-- 
colored glass  is  formed,  known  by  the  name  of  smalt,  and 
used  in  the  arts  for  communicating  the  blue  color  to  - 
porcelain,  and  earthen-ware. 

The  protoxide  is  easily  precipitated  from  its  salts  by  alka- 
lies; the  precipitates  are  of  a  blue  or  pale  pink  color;  dis- 
solved in  excess  of  alkali. 

|  Oxide  of  Cobalt  (3Co  +  4O.  120.3)  if  probably  a  compound  of  the 
peroxide  and  the  protoxide. 

Peroxide  of  Cobalt  (2Co  +  3O.  83)  is  obtained  as  a  black 
hydrate  with  2  equivs.'of  water,  when  chloride  of  cobnlt  is 
decomposed  by  chloride  of  lime.  The  water  is  driven  <>•} 
by  exposure  to  a  heat  of  600°  or  700°.  It  combines  u  ith 
none  of  the  acids,  and,  when  strongly  heated,  is  decomp< 
and  resolved  into  the  protoxide  and  oxygen. 

Chloride  of  Cobalt  (Co  +  Cl.  64.92)  is  obtained  by  dis- 
solving metallic  cobalt,  or  either  of  its  oxides,  in  hydrochlo- 
ric acid.  The  solution  is  of  a  pink  color,  and  yields,  on 
evaporation,  small  crystals  of  the  same  color.  When  these 
crystals  are  deprived  of  their  water  of  crystallization,  they 
assume  a  blue  color  —  a  property  on  which  is  founded  its 
use  as  a  sympathetic  ink. 

Ezp.  Write  on  paper  with  a  dilute  solution  of  the  chloride,  and 
expose  it  to  a  gentle  heat;  it  becomes  blue.  This  solution  is  called 
Hillot's  sympathetic  ink,  and  is  described  by  some  chemists  as  a  mu- 
riate, of  cobalt ;  but  Turner  thinks  it  a  chloride,  analogous  to  several 
other  compounds  generally  described  as  muriates  of  the  metals. 

Exp.  Draw  the  branches  of  a  tree  with  India  ink,  and  put  on  the 
foliage  with  the  chloride  of  cobalt.  When  cold,  the  foliage  does  not 
appear,  but  shows  itself  on  the  application  of  heat.  A  landscape  may 


Compounds  of  Nickel.  253 

be  represented,  in  this  manner,  as  wintry  or  vernal,  according  as  the 
heat  is  increased  or  diminished. 

Sulphurets  of  Cobalt.  Cobalt  unites  with  sulphur  in  three 
proportions. 

The  Protosulphurct  (Co  -|-  S.  45.6)  is  formed  "by  throwing  fragments 
of  sulphur  on  red-hot  cobalt ;  has  a  gray  color,  a  metallic  lustre,  and 
crystalline  texture. 

The  Sesquisulphuret  of  Cobalt  (2Co-f-3S.  107.3)  is  formed  by  pass- 
ing a  current  of  hydrosulphuric  acid  gas  over  the  oxysulphuret,  at  a 
red  heat. 

Tlie.  Bisulphuret  (Co-}-2S.  61.7)  is  prepared  by  heating  below  red- 
ness, in  a  glass  tube,  2  parts  of  the  carbonate  of  the  oxide  of  cobalt, 
intimately  mixed  with  3  of  sulphur. 

Subphosphuret  of  Cobalt  (3Co-f-2P.  119.9)  is  obtained  by  the  action 
of  pliosphureted  hydrogen  on  chloride  of  cobalt.  It  is  a  pulverulent, 
gray  solid. 


NICKEL.     Symb.  Ni.     Equiv.  29.5.     Sp.  gr.  8.2579. 

« 
Nickel  was  discovered  by  Cronstedt  in  1751,  in  the  kup- 

fer  nickel  (copper  nickel)  of  Westphalia.  The  term  nickel 
was  applied  to  the  ore  because  it  looked  like  copper,  but  did 
not  yield  it.  It  exists  also  in  meteoric  iron. 

Process.  Nickel  may  be  extracted  from  the  ore,  —  which 
is  an  arscniuret  of  nickel,  containing  small  quantities  of 
sulphur,  copper,  cobalt,  and  iron,  —  or  from  speiss ;  also  an 
arseniuret  which  is  obtained  in  forming  smalt  from  the 
roasted  ores  of  cobalt.  This  metal  is  obtained  by  heating 
the  oxalate  or  the  oxide  with  charcoal  in  close  vessels.* 

Properties.  Color  white,  intermediate  between  tin  and 
silver;  strong  metallic  lustre;  ductile  arid  malleable;  at- 
tracted by  the  magnet,  and,  like  iron  and  cobalt,  may  be 
rendered  permanently  magnetic ;  a  little  less  infusible  than 
iron ;  oxidized  at  a  red  heat,  and  by  nitric  acid. 

Compounds  of  Nickel. 

Protoxide  of  Nickel  (Ni-|-O.  37.5)  is  formed  by  heating 
the  carbonate,  oxalate,  or  nitrate,  to  redness,  to  drive  off  the 
acid. 

*  For  processes,  see  Turner's  Elements,  p.  351. 
22 


254  Metals.  —  Arsenic. 

Properties.  Color  at  first  an  ash-gray,  but,  when  exposed 
to  a  white  heat,  it  is  of  a  dull  olive-green.  This  is  the 
strong  alkaline  base  of  the  metal,  and  nearly  all  the  salts 
have  a  green  tint.  Pure  alkalies  precipitate  this  oxide  from 
its  salts,  as  a  hydrate  of  a  pale  green  color.  The  alkaline 
carbonates  and  hydrosulphurets  also  precipitate  it  from  its 
salts,  the  former  as  a  carbonate,  the  latter  as  a  sulphuret  of  a 
black  color. 

Sesquioxlde  of  JYYdW  (2Ni  +  3O.  83)  is  formed  by  transmitting 
chlorine  through  water,  in  which  the  hydrate  of  the  protoxide  is  sus- 
pended. It  has  a  black  color,  does  not  unite  with  acids,  and  is  decom- 
posed at  a  red  heat. 

Cltlnrnit  <>J\\ickel  (Ni-j-Cl.  64.92)  is  formed  by  the  action  of  hydro- 
chloric acid  upon  metallic  nickel,  or  one  of  its  oxides;  an  « in.  r.ijd- 
green  solution  is  formed,  and,  on  evaporation,  yields  crystals  ol  tin- 
same  tint,  which  deliquesce  in  moist  air,  and  effloresce  if  lite,  air  is  dry. 

Protofuljihuret  of  Mfkcl  (Ni  +  8.  45.6)  is  formed  by  a  similar  pro- 
cess with  the  protosulphuret  of  cdbalt ;  occurs  native  in  acicular 
crystals  —  the  lioarkic*  of  the  Germans.  When  dry,  it  is  of  a  grayish- 
yellow  color,  while  the  precipitates  are  dark  brown ;  soluble  in  nitric 
or  nitrohydrochloric  acid. 

Ditulphuret  ofXickd  (2Ni  +  S.  73.1)  is  obtained  by  passing  hydro- 
gen gas  over  the  sulphate  of  nickel  at  a  red  heat;  color  light  yellow, 
and  is  more  fusible  than  the  preceding. 

Subphofphurtt  ,{f  .YiVAW  (3Ni+2P.  110.9)  is  obtained  by  the  action 
of  hydrogen  on  subphosphate  of  oxide  of  nickel.  Color  black,  solu- 
ble in  nitric  acid,  and  burns  with  a  flame  under  the  blowpipe. 

Cyanuret  of  Mckel  (Ni-f-Cy.  55.89)  is  obtained  by  mixing  in  solu- 
tion a  salt  of  nickel  with  cyanuret  of  potassium.     A  precipii 
formed,  of  a  pale,  apple-green  color,  which  becomes  tinged  with  yellow 
on  drying. 


SECT.  2.  METALS  WHICH  DO  NOT  DECOMPOSE  WATER  AT 
ANY  TEMPERATURE,  AND  THE  OXIDES  OF  WHICH  ARE  NOT 
REDUCED  TO  THE  METALLIC  STATE  BY  THE  SOLE  ACTION 
OF  HEAT. 

j*ftSEJY7C.    Symb.  As.    Equiv.  37.7.    Sp.  gr.  5.8853. 

Arsenic  was  first  discovered  by  Dioscorides,  who  called 
it  Sandarac;  but  its  properties  were  first  investigated  by 
Brandt,  in  1733. 

Natural  History.  It  exists  in  nature,  in  small  quantities, 
rarely  in  a  metallic  state.  It  is  generally  found  in  com- 


Compounds  of  Arsenic.  255 

bination  with  cobalt  and  iron,  and  occasionally  with  other 
metals 

Process.  Metallic  arsenic  is  obtained  by  roasting  the  ores 
in  a  reverberatory  furnace ;  as  the  arsenic  is  expelled  by  heat, 
it  combines  with  oxygen,  and  condenses  into  thick  cakes  on 
flu-  chimney.  These  cakes  are  purified  by  a  second  sublima- 
tion, and  constitute  the  white  oxide  of  arsenic  —  a  virulent 
poison.  This  substance  is  then  mixed  with  twice  its  weight 
oi'  bleu  k  flux  *  exposed  with  charcoal  to  a  red  heat  in  a  Hes- 
sian crucible;  and  the  metal  is  sublimed  and  collected  in  an 
empty  crucible,  which  is  placed  over  the  other,  and  kept  cool 
for  the  purpose  of  condensation. 

Properties.  Arsenic  is  a  very  brittle  metal,  of  a  steel-gray 
color,  high  metallic  lustre,  and  of  a  crystalline  structure. 
When  heated  to  356°,  it  sublimes  without  fusion,  and  may  be 
collected  in  close  vessels  without  change ;  but,  when  thrown 
on  a  red-hot  iron,  it  burns  with  a  blue  flame  and  white 
smoke,  giving  off  a  strong  odor  of  garlic—  a  property  which 
belongs  to  no  other  metal,  unless  it  be  zinc;  when  thus 
heated  in  the  open  air,  it  is  converted  into  the  white  oxide 
of  arsenic.  Exposed  at  common  temperatures  of  the  air,  it 
oxidizes  slowly,  forming  the  substance  called  jly-powder, 
which  is  a  mixture  of  the  oxide  and  the  metal. 

Arsenic  detonates  with  some  of  the  salts,  and  decomposes 
them. 

Exp.  Take  3  parts  of  chlorate  of  potassa,  and  1  of  arsenic,  finely 
powdered,  and  cautiously  mixed  together. 

1.  Place  a  small  quantity  on  an  anvil,  and  strike  it  with  a  hammer; 
the  arsenic  will  instantly  combine  with  the  salt,  producing  an  explosion 
with  flame. 

2.  Set  it  on  fire,  and  it  will  burn  rapidly. 

3  Throw  it  into  concentrated  sulphuric  acid,  and  a  bright  flash  of 
light  will  be  perceived  at  the  moment  of  contact. 

Uses.  Arsenic  is  used  in  the  arts.  It  renders  glass 
white. 

Compounds  of  Arsenic. 

Arsenious  acid,  (2As-|-3O,  99.4,)  commonly  called  white 
arsenic  and  white  oxide  of  arsenic,  may  be  formed  by  the 

*  Prepared  by  detonating,  in  a  crucible,  1  part  of  nitre  with  2  of 
the  crystals  of  tartar. 


256  Metals.  —  A  rsenic. 

combustion  of  the  metal ;  but  the  white  arsenic  of  commerce 
is  obtained  from  the  arseniurets  of  cobalt,  by  sublimation. 

Properties.      Arsenious   acid   is   white,  semi  transparent, 

and,  when  first  formed,  of  a  vitreous  lustre  and  conchoid ;ti 
fracture.  Its  acid  taste  is  owing  to  the  inflammation  which 
it  produces ;  it  has  a  faint  impression  of  sweetness.  Its 
sp.  gr.  is  3.7;  has  two  crystalline  forms,  but  is  usually  found 
in  six-sided  scales,  derived  from  a  rhombic  prism ;  soluble 
in  water. 

It  is  one  of  the  most  virulent  poisons  known ;  and,  as  it  is 
sometimes  accidentally  or  intentionally  taken,  it  is  a  frequent 
cause  of  death,  and  a  subject  of  judicial  investigation.  Hence 
the  importance  of  pointing  out  the  most  effectual  modes  of 
detecting  its  presence. 

Tests.  The  most  valuable  are  the  ammoniac o-nitr ate  of 
silver,  ammoniaco-sulphate  of  copper,  hydrosulphuric  acid, 
and  hydrogen  gas. 

1.  Obtain  as  large  a  quantity  of  the  liquid  from  the  stom- 
ach as  possible.     This,  with  parts  of  the  stomach,  should  be 
put  into  pure  water,  filtered  and  evaporated,  so  as  to  obtain 
a  concentrated  solution;  add  to  this,  ammoniacal  nitrate  of 
silver,*  and  if  arsenic  is  present,  a  yellow  —  arseniate  of  sil- 
ver—  will  be  thrown  down. 

2.  Add  to  the  suspected  liquid  ammoniacal  sulphate  of 
copper,t   and    a   green   precipitate   will    be  formed,    called 
Scheele's  green. 

3.  Pass  into  the  liquid,  hydrosulphuric  acid,  and  if  aryni- 
ous    acid    is  present,   orpiment,   or    the  sesquisulphuret  of 
arsenic  will  be  formed,  giving  to  the  liquor  a  yellow,  turbid 
appearance.     This  sulphuret  should  then   be   dried,   mixed 
with  black  flux,  carefully  introduced  into  a  glass  tube,  and 
heated  by  a  spirit  lamp;  the  sulphuret  will  be  decomposed, 
and   metallic  arsenic  appear  on  the  cool   parts  of  the  tube. 
This  is  a  very  satisfactory  test ;   but  if,  on  heating  the  sub- 

*  Prepared  by  dropping  into  a  strong  solution  of  ni train  of  silver, 
ammonia,  till  the  oxide  of  silver,  first  precipitated,  is  nearly  all  dis- 
solved. 

t  Prepared  in  Ihe  same  way  with  the  preceding,  by  using  the  sul- 
phate of  copper,  instead  of  the  nitrate  of  silver. 


Compounds  of  Arsenic.  257 

stance  thus  deposited,  it  rises  up  in  white  fumes,  with  an 
alliaceous  odor,  and  is  deposited  in  white,  octohedral  crystals, 
we  may  be  sure  that  arsenic  is  present. 

4.  Introduce  a  quantity  of  the  suspected  liquid  into  a 
Florence  flask,  having  a  jet  pipe  and  a  stop-cock  attached, 
with  zinc  and  sulphuric  acid;  the  water  will  be  decomposed, 
and  the  nascent  hydrogen,  in  passing  through  the  water  con- 
taining  arsenious  acid,  will  form  arseniureted  hydrogen; 
and  on  burning  the  gas,  as  it  issues  from  the  jet,  metallic 
arsenic  will  be  deposited  on  a  plate  of  glass  or  porcelain, 
held  over  the  flame. 

Any  one  of  these  tests,  however,  should  not  be  depended 
upon  in  a  case  where  the  life  of  a  fellow-being  is  at  stake,  as 
other  metals,  such  as  antimony,  will  sometimes  present  a 
similar  appearance;  but  if  the  suspected  substance  be  tested 
by  each  of  the  four  ways  mentioned,  there  can  be  no  doubt 
but  that  it  contains  arsenious  acid. 

Its  action  upon  animals,  whether  taken  into  the  stomach,  or  applied 
to  wounds,  is  attended  by  pain  and  vomiting;  and  if  life  be  prolonged 
beyond  twenty-four  hours,  diarrhoea,  a  sensation  of  heat,  and  extreme 
pain  in  the  stomach  and  intestines,  succeed,  pulse  feeble,  countenance 
anxious,  skin  livid, often  attended  by  eruptions. 

The  best  antidote  is  per  hydrate  of  iron,  with  a  small  quantity  of  am- 
monia. In  cases  rapidly  fatal,  extreme  faintness,  cold  sweats,  attended 
with  slight  convulsions,  are  experienced.  (See  Christison  on  Poisons.) 

Arsenic  has  the  properly  of  preserving  from  decay  the  bodies  of 
those  poisoned  with  it.  The  stomach  and  intestines  have  thus  been 
found  entire  two  years  and  a  half  after  death. 

Arsenic  Acid  (2As-|-5O.  115.4)  is  formed  by  dissolving 
arsenious  acid  in  concentrated  nitric,  mixed  with  a  small 
quantity  of  hydrochloric  acid,  distilling  in  a  glass  vessel  until 
it  acquires  the  consistency  of  sirup,  and  then  heating  nearly 
to  redness,  in  a  platinum  crucible,  to  expel  the  nitric  acid. 

Properties.  It  has  a  sour,  metallic  taste,  reddens  the  vege- 
table blue  colors,  and  combines  with  alkalies,  forming  arse- 
niates.  It  is  decomposed  by  hydrosulphuric  acid.  This 
acid  is  also  an  active  poison. 

Protochloride  of  Arsenic  (AsCl.  73.12)  is  prepared  by  heating  in  a 
retort,  to  nearly  212°,  arsenious  acid,  with  ten  times  its  weight  of  con- 
centrated sulphuric  acid,  and  throwing  them  in  fragments  of  common 
salt. 

SesquirhJoride  of  Arsenic  (As2Cl3.  181.66)  is  formed  by  the  sponta- 
neous combustion  of  powdered  arsenic  in  chlorine  gas.  It  is  a  color- 

22* 


253  Metals.  —  Chromium. 

less,  volatile  liquid,  giving  off  fumes,  on  exposure  to  the  air;  hence 
called  fuming  liquor  of  arsenic. 

Periodidl  of  Arsenic  (2As-|-51.  706.0)  is  formed  by  gently  heating 
arsenic  with  iodine.  It  is  a  deep  red  compound,  decomposed  by 
water. 

Protohyduret  of  Arsenic  (As-f-H.  38.7)  is  prepared  by  the  action  of 
water  on  an  alloy  of  arsenic  and  potassium. 

Sesquibromide  of  Arsenic'.  2As  +  3Br.  310.6.  When  arsenic  and 
bromine  are  brought  into  contact,  they  instantly  unite  with  vivid  evo- 
lution of  light  and^heat. 

Arscniurcted  Hydrogen.  2As-|-3H.  78.4.  This  gas 
was  discovered  by  Scheele.  It  is  generally  made  by  digest- 
ing an  alloy  of  tin  and  arsenic  in  hydrochloric  acid.  It  is 
colorless;  has  a  fetid  odor  resembling  garlic;  sp.  gr.  2. ()<).">: 
extinguishes  burning  bodies,  but  burns  with  a  blue  flame. 
It  is  poisonous  in  a  high  degree,  having  proved  fatal  to  Ai. 
Gehleu.  It  is  decomposed  by  chlorine,  iodine,  caloric,  and 
even  atmospheric  air;  it  forms  with  oxygen  an  explosive 
mixture. 

Protosulphuret of  Arsenic.  As+S.  53.8.  This  subst .-H-T 
exists  in  the  mineral  kingdom,  and  is  called  realgar.  It 
may  be  formed  by  heating  arsenious  acid  with  half  its  weight 
of  sulphur,  until  the  mixture  is  perfe/itly  fused.  It  is  ocys- 
talline,  transparent,  and  of  a  ruby-red  color. 

Sesquisulphurct  <ff  Arsenic.  2As  +  3S.  123.7.  This  in 
the  native  state  is  called  orpiment. 

Process.  It  may  be  formed  by  fusing  arsenious  acid  and  sulphur ; 
but  it  is  purer,  if  obtained  by  passing  hydrosulphuric  acid  gas  through 
a  solution  of  arsenious  acid. 

Properties.  This  substance  has  a  rich,  yellow  color,  and 
is  employed  as  a  pigment.  It  is  the  coloring  principle  in 
the  paint  called  king's  yellow. 

Persvlphuret  of  Arsenic  (2As-|-5S.  155.9)  is  formed  by  passing 
hydrosulphuric  acid  through  a  moderately  strong  solution  of  arsenic 
acid.  It  resembles  qrpiment  in  color.  The  sulphurets  of  arsenic  are 
poisonous. 


CHROMIUM.     Symb.  Cr.     Equiv.  26.    Sp.  gr.  5.9. 

Chromium*  was  discovered  in  1797,  by  Vauquelin,  in  a 
beautiful  red  mineral,  the  native  chromate  of  lead.     It  exists 


color,  from,  its  remarkable  tendency  to  form  colored  com- 
pounds. 


e 


Compounds  of  Chromium.  259 

also  in  chromate  of  iron,  a  native  mineral  found  abundantly 
in  Europe,  and  also  in  this  country. 

Process.  This  metal  has  been  obtained  only  in  small 
quantities,  owing  to  its  affinity  for  oxygen.  The  oxide  may 
be  deprived  of  its  oxygen,  by  heating  it  with  charcoal  in  a 
smith's  forge. 

Properties.  A  brittle  metnl,  of  a  grayish-white  color,  and 
very  infusible.  It  is  oxidized  by  heating  it  with  nitre,  and 
converted  into  chromic  acid. 

Compounds  of  Chromium. 

Sesquioxide  of  Chromium.  2Cr-f-3O.  80.  Exists  native 
in  the  emerald. 

Procfss.  It  is  prepared  by  dissolving  chromate  of  potassa  in  water, 
and  mixing  it  with  a  solution  of  nitrate  of  mercury,  when  a  yellow- 
colored  precipitate  —  the  chromate  of  mercury  —  is  formed.  When  this 
salt  is  heated  to  redness  in  an  earthen  crucible,  the  mercury  is  driven 
off,  and  the  chromic  acid  is  resolved  into  oxygen,  and  oxide  of  chro- 
mium. 

Properties.  O\ide  of  chromium  is  of  a  green  color,  very 
infusible,  insoluble  in  water,  and  after  being  strongly  heated, 
resists  the  action  of  the  most  powerful  acids  ;  heated  with 
nitre,  it  is  converted  into  chromic  acid.  Fused  with  borax 
or  vitreous  substances,  it  communicates  to  them  a  beautiful 
green  color.  Hence  its  utility  in  the  arts.  It  unites  with 
acids,  and  forms  green-colored  salts. 

Chromic  Acid  (Cr-j-3O.  Equiv.  52)  may  be  obtained 
from  the  native  chromate  of  iron. 

Process.  It  is  best  prepared  by  transmitting  the  gaseous  fluoride 
of  chromium  into  water  contained  in  a  vessel  of  silver  or  platinum; 
when,  by  mutual  decomposition  of  the  gas  and  the  water,  hydrofluoric 
and  chromic  acids  are  generated.  —  T. 

Properties.  This  acid  is  black  while  warm,  and  dark  red 
when  cold.  When  dry,  according  to  Hayes,  it  is  yellowish- 
brown,  very  soluble  in  water,  rendering  it  red  and  yellow. 
When  a  heated  concentrated  solution  cools,  it  deposits  red 
crystals,  very  deliquescent.  The  solution  has  an  acid,  astrin- 
gent taste,  and  bleaches  litmus  paper.  It  destroys  most  vege- 
table and  animal  coloring  matters.  Hence  its  use  in  calico- 
printing.  It  is  characterized  by  its  color,  and  by  forming 
colored  salts  with  alkaline  bases. 


260  Metals.  —  Vanadium. 

Sesquicldoride  of  Chromium  (2Cr-f-3Cl.  102.26)  may  be  prepared 
by  transmitting  dry  chlorine  gas  over  a  mixture  of  oxide  of  chromium 
and  charcoal,  heated  to  redness  in  a  porcelain  tube  ;  when  the  sesqui- 
chloride  gradually  collects  as  a  crystalline  sublimate  of  a  peach-purple 
color.  — T. 

Terchloride  of  Chromium  (Cr-f  3C1.  134.26)  IB  Vmied  by  the  action 
of  fuming  sulphuric  acid  on  a  mixture  of  chromate  of  lead  and  chloride 
of  sodium. 

Oxychloride  of  Chromium.    CrCP  +  2CrO3.  238.26. 

Sesffuifluoride  of  Chromium  (2Cr  -f-  3F.  114.04)  is  formed  by  uissolv- 
ing  the  oxide  in  hydrofluoric  acid,  and  evaporating  to  dryness. 

Ttrftuorid*  of  Chromium.   Cr  -f  3F.  28  -f  5<i.04  =  84 .04 . 

Se>quisulpkvret of  Chromium  (2Cr -{-38.  104.3)  may  be  obtained  by 
heating  in  close  vessels  a  mixture  of  sulphur  and  the  hyd rated  oxide. 
It  is  ofa  dark-gray  color,  acquiring  a  metallic  lustre  by  irictimi. 

Protophosphuret  of  Chromium  (Cr-fP  or  CrP.  43.7')  is  prepared  by 
passing  phosphureted  hydrogen  gas  over  the  sesquichloride  of  chro- 
mium at  a  red  heat;  a  black  compound,  burning  before  the  blowpipe, 
with  a  flame  of  phosphorus. 


VANADIUM.    Symb.  V.     Equiv.  68.5. 

Vanadium  was  discovered  by  Sefstrom,  in  1830.  It  de- 
rives its  name  from  Vanadis,  a  Scandinavian  deity. 

Natural  History.  It  exists  in  the  iron  ore  of  Taberg, 
Sweden,  and  is  found  in  great  abundance  in  the  slag  formed 
by  .converting  the  cast  iron  of  Taberg  into  malleable  iron. 
It  was  also  found  by  Johnson,  at  Wanlock-Head,  Scotland, 
where  it  occurs  as  a  vanadiate  of  lead. 

Process.  It  has  been  obtained  in  various  ways  —  by  heat- 
ing vanadic  acid  with  potassium,  and  by  the  decomposition 
of  the  chloride  of  vanadium.* 

Properties.  When  obtained  by  means  of  potassium,  it  is 
a  brittle,  black  substance  ;  but  when  prepared  by  decompo- 
sing the  chloride,  it  is  white,  resembling  silver,  of  a  strong 
metallic  lustre.  It  is  not  oxidized  by  air  or  water  ;  boiling 
sulphuric,  hydrochloric,  and  hydrofluoric  acids  do  not  affect 
it,  but  it  is  dissolved  by  nitric  and  nitrohydrochloric  acids, 
and  the  solution  has  a  fine,  dark  blue  color. 

*  For  processes,  see  Turner's  Elements. 


Compounds  of  Vanadium  —  Molybdenum.          261 

Compounds  of  Vanadium. 

Protoxide  of  Vanadium  (V-f-O.  7G.5)  may  be  obtained  by  heating 
vanadic  acid  with  charcoal  or  hydrogen  gas.  It  is  a  dark  brown,  or 
black,  substance,  soluble  in  nitric  acid. 

Binoxide  of  Vanadium  (V-J-2O.  84.5)  may  be  prepared  by  heating 
to  full  redness  10  parts  of  the  protoxide,  with  12  of  vanadic  acid,  in  a 
vessel  filled  with  cnrbonic  acid.  It  is  black,  very  infusible,  and  insolu- 
ble jn  water.  Its  salts  have  a  blue  color.  It  acts  the  part  of  an  acid 
by  uniting  with  alkaline  bases. 

Vanadic  Acid  ( V -(- 3O.  92.5)  is  tasteless,  insoluble  in 
alcohol,  and  very  slightly  soluble  in  water.  It  is  easily  de- 
composed by  heating  it  with  combustible  matter,  and  in  solu- 
tion by  all  deoxidizing  agents.  It  unites  with  bases  often  in 
two  or  more  proportions  ;  most  of  its  neutral  salts  are  yellow. 
It  is  distinguished  from  all  other  acids,  except  the  chromic, 
by  its  color,  and  from  this  acid  by  the  action  of  deoxidizing 
substances,  which  give  a  blue  solution  with  the  former,  and 
green  with  the  latter.* 


MOLYBDENUM.     Symb.  Mo.     Equiv.  47.7.     Sp.  gr.  8.615. 

Molybdenum  was  discovered  in  1775. 

Process.  It  was  obtained  from  the  native  sulphuret,  by 
digesting  it  in  nitrohydrochloric  acid,  and  heating  the  mo- 
lybdic  acid,  thus  formed,  in  connection  with  charcoal. 

Properties.  It  is  a  brittle  metal,  of  a  white  color,  and 
very  infusible.  Its  properties  are  imperfectly  known. 

Protoxide  of  Molybdenum  (Mo-f-O.  55.7)  is  obtained  by 
precipitating  the  hydrochloric  solution  of  molybdic  acid  by 
zinc,  when  a  brown  hydrate  is  formed,  giving  dark  colored 
solutions  with  the  acids. 

Binoxide  of  Molybdenum  (Mo  -j-  O.  63.7)  is  prepared  by  putting  a 
mixture  of  molybdate  of  soda  and  sal-ammoniac,  in  fine  powder,  in  a 
red-hot  crucible,  instantly  covering  it,  and  continuing  the  heat  until 


*  The  bichloride  of  vanadium,  (VC12.  68.5  +  70.34  =  139.34;)  the 
tercldoride  of  vanadium,  (VCR  68.5  +  106.26  =  174.76  ;)  the  bibromide 
of  ramulium,  ( VBr2.  68.5  -f- 156.8  =  225.3  ;)  the  bisuljthuret  of  vana- 
dium, (VS2.  68.5  -(-  32.2  =  100.7  ;)  the  tersulphuret,  (VS3.  68  5  -f  48.3 
=  llf).8,)  are  unimportant  compounds,  for  a  description  of  which,  see 
Turner's  Elements,  p.  365. 


262  Mttah.  —  Tungsten. 

vapors  of  sal-ammoniac  cease  to  arise.    This  is  a  deep  brown  anhydrous 
powder,  insoluble  in  acids. 

Molybdic  Acid .(Mo-f  3O,  or  MO3  71.7)  may  be  obtained 
by  roasting  the  native  sulphuret  in  an  open  crucible,  kept  at 
a  low  red  heat,  and  stirred  until  sulphurous  acid  ceases  to 
escape.  The  yellow  powder,  thus  formed,  is  treated  with 
ammonia ;  the  filtered  solution  evaporated,  again  dissolved 
in  water  and  ammonia,  and  crystallized ;  the  ammonia  is 
then  expelled  by  gentle  heat. 

It  is  a  white  powder ;  sp.  gr.  34.9  ;  fuses  at  a  red  heat  into 
a  yellow  liquid  ;  slightly  soluble  in  water.* 


TVNGSTEJt.    Symb.  W.     Equiv.  94.8.     Sp.  gr.  17.5. 

Tungsten  is  found  native  in  the  mineral  wolfram. 

Process.  It  is  obtained  by  exposing  a  mixture  of  tungstic 
acid  and  charcoal  to  a  strong  heat. 

Properties.  It  is  a  very  hard,  brittle  metal,  resembling 
iron  in  color,  and,  by  the  action  of  heat  and  air,  converted 
into  tungstic  acid. 

Compounds  of  Tungsten. 

Binoxide  of  Tungsten  (W  +  2O.  110.8)  is  prepared  by 
the  action  of  hydrogen  gas  on  tungstic  acid,  at  a  low  red 
heat.  It  has  a  brown  color,  resembling  copper  when 
polished. 

Tungstic  Acid  (W  +  3O.  118.8)  may  be  obtained  by 
heating  the  binoxide  to  redness  in  open  vessels.  It  is  of  a 
yellow  color,  insoluble  in  water,  and  has  no  action  on  litums 
paper. 

Bichloride  of  Tungsten  (W  +  2C1.  165.64)  is  formed  by 
heating  tungsten  in  chlorine  gas.t 

*  For  the  preparation  of  the  protochloride  of  molylnl<intm,  (Mod. 
83.12  ;)  the  bichloride  of  molybdenum,  (MoCl».  118.54  ;)  the  trrrhluride 
of  molybdenum,  (Mod3.  153.90;)  the  tersulphurrt  nf  molybdermm, 
(MoS3.  D6,)  and  the  persulphuret  of  molybdenum,  (MoS4.  112.1,)  the 
student  is  referred  to  Turner's  Element^,  p.  369. 

t  For  a  description  of  the  tercliloride  of  tungsten,  (WC13.  201.6  :)  bi- 
sulphuret  of  tungsten,  (WS2.  126;)  and  tcrsulpliurct  of  tungsten,  (\VS3. 
143.1,)  see  Turner's  Chemistry. 


Columbium  —  Antimony.  263 


COLUMBIUM.     Symb.Ta.     Equiv.  185. 

Columbium  was  discovered  in  1801,  by  Hatchett,  in  a 
black  mineral  in  the  British  Museum,  which  had  been  sent 
by  Governor  Winthrop  to  Sir  Hans  Sloane,  from  Haddam,  in 
Connecticut.** 

Process.  It  is  obtained  by  heating  potassium  with  the 
double  fluoride  of  potassium  and  columbium. 

Properties.  Obtained  in  this  way,  it  is  a  black  powder, 
and  a  non-conductor  of  electricity,  but  a  perfect  conductor 
in  a  more  dense  state.  It  acquires  a  metallic  lustre  by  pres- 
sure ;  of  an  iron-gray  color ;  fuses  at  a  higher  temperature 
than  glass ;  heated  in  the  open  air,  it  takes  lire,  and  is  con- 
verted into  columbic  acid.  It  is  easily  dissolved  into  nitro- 
hydrofluoric  acid. 

Compounds  of  Columbium. 

Binozide  of  Colnnil/ium  (Ta-(-2O.  201)  may  be  formed  by  exposing 
columbic  acid  in  a  crucible,  lined  with  charcoal,  and  luted  to  exclude 
the  air,  for  an  hou,r  and  a  half,  to  an  intense  heat.  When  reduced  to 
powder,  it  is  a  dark  brown  substance,  not  acted  upon  by  acids,  but  con- 
verted into  columbic  acid  by  fusion  with  potassa  or  nitre. 

Ctilumbic  Acid  (Ta  -f-  3O.  201))  is  formed  from  the  native  colurnbates, 
by  fusing  the  ores  with  three  or  four  times  their  weight  of  carbonate  of 
potassa,  and  precipitating  the  white  hydrate  by  acids. 

Properties.  Hydrated  columbic  acid  is  tasteless,  insolu- 
ble in  water,  and  communicates  a  red  tinge  to  moistened  lit- 
mus paper  ;  heated  to  redness,  the  water  is  expelled,  and  the 
an  hydrous  columbic  acid  remains.f 


JXTIMOJYY.     Symb.  Sb.     Equiv.  64.6.     Sp.  gr.  6.702. 

History.     Antimony  was  discovered  by  Basil  Valentine, 
in  the  fifteenth  century.     It  derived  its  name  from  anti  monk, 


*  Tantalum,  discovered  by  Ekeberg,  is  identical  with  this  metal. 

t  For  a  description  of  the  terchloride  of  columbium,  (Ta-f-3Cl. 
291 .26;)  the  terfluoride  of  columbium,  (Ta  +  3F.  241.04  ;)  and  the  sul- 
phuret  of  columbium,  composition  uncertain,  see  Turner's  Chemistry. 


264  JMctals.  —  A  ntimony, 

from  its  having  proved  fatal  to  some  monks,  to  whom  it  was 
given  as  a  medicine. 

It  is  found  native  in  Sweden,  France,  and  the  1 1  art  /  ;  but 
generally  occurs  as  a  sulphuret. 

Process.  It  may  be  obtained  by  heating  the  native  sul- 
phuret in  a  covered  crucible,  with  half  its  weight  of  iron- 
filings  ;  the  sulphur  unites  with  the  iron,  and  the  metal  ap- 
pears in  the  bottom  of  the  crucible.  Procured  in  this 
it  is  not  absolutely  pure,  and,  for  chemical  purposes,  it  should 
be  procured  by  heating  the  oxide  with  an  equal  weight  of 
cream  of  tartar. 

Properties.  A  brittle  metal,  of  a  white  oolor ;  fuses  at 
810°,  and,  on  cooling,  has  a  lamellated  texture,  and  often 
yields  crystals ;  burns  with  great  brilliancy  when  placed  on 
ignited  charcoal,  under  a  current  of  oxygen  gas. 

Compounds  of  Antimony. 

Sesquioxidt  of  Antimony  (2Sb  -f-  3O.  153.2)  is  obtained 
by  subjecting  antimony  in  a  covered  crucible  to  a  white  heat, 
and  then  exposing  it  to  the  air ;  a  white  vapor  arises,  and 
condenses  jn  fine  crystals  of  silver  whiteness. 

It  is  the  only  «xide  which  forms  regular  salts.  It  is  the 
base  of  emetic  tartar,  and  the  tartrate  of  antimony  and  po- 
tassa.  The  test  of  antimony  in  solution  is  the  hydrosulphuric 
acid,  which  yields  an  orange-colored  precipitate. 

Antimonious  Acid  (2Sb-f-4O.  .161.2)  is  generated  when 
the  oxide  is  exposed  to  heat  in  open  vessels.  It  is  white 
when  cold,  and  yellowish  when  heated ;  very  infusible  and 
fixed  in  the  fire,  by  which  it  is  distinguished  from  the  oxide  ; 
insoluble  in  water  and  in  acids,  after  being  heated  to  redness. 

Antimonic  Acid  (2Sb  -|-5O.  169.2)  may  be  obtained  as  a 
white  hydrate,  either  by  digesting  the  metal  in  strong  nitric 
acid,  or  by  dissolving  it  in  nitrohydrochloric  acid,  concen- 
trating by  heat  to  expel  excess  of  acid,  and  throwing  the 
solution  into  water. 

It  is  decomposed  at  a  red  heat,  and  converted  into  anti- 
monious  acid. 

Sesquichl&ride  of  Antimony  (2Sb-|-3Cl.  235.46)  is  generated  by  the 
spontaneous  combustion  of  antimony  in  chlorine  gas.  It  is  a  soft  solid, 


Uranium.  265 

called  butter  of  antimony  ;  easily  fused,  and  deliquesces  when  ex- 
posed to  the  air.* 

Sesquisulphuret  of  Antimony.  2Sb-|-3S.  177.5.  This  is  the  princi- 
pal ore  of  the  metal,  and  hence  is  generally  employed 'in  making  the 
preparations  of  antimony.  It  is  of  an  earthy  appearance,  but  is  some- 
times found  in  acicular  crystals,  of  a  red-gray  color  and  metallic  lustre  ; 
sp.  gr.  4.62.  It  may  be  formed  artificially  by  fusing  together  antimony 
and  sulphur. 

Oxysulphuret  of  Antimony  is  composed  of  2  equiv.  of  2  Sb  -f-  3S 
and  1  equiv.  of  2SbO3  =508.2.  This  occurs  native  —  the  Ted  antimony 
of  mineralogists.  Glass,  liver,  and  crocus  of  antimony  are  of  a  similar 
nature. 

Kermts  Mineral  is  formed  by  boiling  the  sesquisulphuret  with  a 
solution  of  potassa  or  soda.  On  neutralizing  the  cold  solution,  a  simi- 
lar substance,  the  golden  sulphuret,  is  precipitated.! 

Alloys.  Printers1  types  are  formed  of  3  parts  of  lead,  1 
of  antimony,  and  a  little  copper. 

Piwtcr  is  an  alloy  of  12  parts  of  tin,  1  of  antimony,  with 
a  small  addition  of  copper.  The  white  metal  for  teapots  is 
an  alloy  of  100  parts  of  tin,  8  of  antimony,  2  of  bismuth,  and 
2  of  copper. 


URANIUM.     Symb.  U.     Equiv.  217.     Sp.  gr.  9. 

Uranium  was  discovered  by  Klaproth,  in  1789.  It  derives 
its  name  from  the  planet  discovered  the  same  year,  (Uranus.) 
It  exists  in  pitch  blende,  and  is  obtained  from  it  by  heating 
the  ore  to  redness,  and  digesting  its  powder  in  pure  nitric 
acid,  diluted  with  3  or  4  parts  of  water.  Its  properties  are 
not  well  known. 

Protoxide  of  Uranium  (U-|-O.  225)  is  obtained  by  de- 
composing the  nitrate  of  the  sesquioxide  by  heat.  It  is  of  a 
dark  green  color,  very  infusible,  and  readily  oxidized  by 
nitric  acid  ;  used  in  the  arts  to  give  a  black  color  to  porce- 
lain. 

*  Bichloride  of  antimony  ;  2Sb-f-4Cl.  270.88.  Perchloride  of  anti- 
mony ;  2Sb  -f-  5C1.  306.3.  Oxychloride  of  antimony  ,•  2  equiv.  of  2Sb  -f- 
3C1.  and  9  equiv.  of  SbO3=  1849.72.  Bromide  of  antimony,  composi- 
tion unknown. 

t  Bisulnhuret  of  antimony;  2Sb  +  4S.  193.6.  P 'er sulphur et  of  anti- 
mony; 2Sb  +  5S.  209.7.  * 

23 


266       .  Metals.  —  Cerium  —  Bismuth. 

Sesquioxide  of  Uranium  (2U  +  3O.  45S)  is  of  a  yellow 
color,  and  combines  with  acids  and  alkaline  bases. 

The  Protochloride  of  Uranium,  (U  +  Cl.  2f>2.42 ;)  the  Sesquicltliirulr 
of  Uranium,  (2U  -+-3C1.  540.26,)  and  the  Sulphuret  of  (7rantum,are  un- 
important compounds.  —  (See  Turner,  page  380.) 


CERIUM.*     Symbr.  Ce.     Equiv.  46. 

Cerium  was  obtained,  by  Hisinger  and  Berzelius,  from  a 
mineral  called  cerite.  It  exists  also  in  the  mineral  called 
allanite,  as  an  oxide,  which  is  very  difficult  to  be  reduced  to 
the  metallic  state.  Vauquelin  obtained  a  small  globule,  not 
larger  than  a  pin's  head,  which  was  not  acted  upon  by  any 
of  the  simple  acids,  and  but  slowly  dissolved  by  the  nitro- 
hydrochloric. 

Compounds  of  Cerium. 

Protoxide  of  Cerium  (Ce  +  O.  Eq.  54)  is  a  white  powder, 
insoluble  in  water.  The  salts,  which  are  soluble,  have  an 
acid  re-action. 

Sesquioxide  of  Cerium  (2Ce  +3O.  1 10)  is  obtained  from  cerite,  and  is 
a  fuwn-red  substance,  soluble  in  several  of  the  acids. 

Protochloride  of  Cerium.     Ce-f-Cl    or  CeCl.     46 -f- 35.42  =  H   I.'. 

Sesquickloride  of  Cerium .   2Ce  +  3C1  or  Ce'Cl3. 92  + 1 06.26  =  1 '. »- . -J»  > 

Protosulphuret  of  Cerium.  Ce  +  S  or  CeS.  G21.  — (See  Turner's 
Chemistry,  p.  381.) 

BISMUTH.    Symb.  Bi.     Equiv.  71.     Sp.  gr.  9.822. 

Native  Bismuth  occurs  in  crystals,  octohedra,  or  cubes, 
containing  arsenic  and  cobalt.  It  is  also  found  combined 
with  sulphur  and  oxygen,  from  which  it  is  obtained  by  the 
aid  of  heat  and  charcoal. 

Properties.  It  is  a  brittle  solid,  generally  composed  of 
broad  plates  of  a  reddish-white  color,  very  fusible ;  melts  at 
476°  Fahr.,  and  forms  very  fine  crystals  by  slow  cooling. 

Exp.  For  this  purpose,  fuse  a  quantity  of  it  in  a  crucible,  and  let  it 
cool  until  a  crust  is  formed ;  break  the  crust  and  pour  out  the  fluid  be- 

*  So  called  from  the  planet  Ceres,  discovered  about  the  same  period. 


Titanium.  267 

neath  ;  the  inner  surface  will  be  lined  with  beautiful  crystals.  Under 
the  compound  blowpipe  it  burns  with  much  brilliancy,  producing  yellow 
fumes  of  protoxide. 


Protoxide  of  Bismuth  (Bi  +  O.  79.  Sp.  gr.  8.211)  may 
be  formed  as  above.  It  forms  salts,  most  of  which  are  white; 
sublimes  at  a  high  temperature  ;  fuses  at  a  full  red  heat  into 
a  brown  liquid.  If  the  nitrate  of  the  protoxide  be  thrown 
into  water,  a  white  precipitate  is  thrown  down,  formerly 
called  magistery  of  bismuth,  and  pearl  white,  which  is  some- 
times used  as  a  paint,  for  improving  the  complexion. 

Sesquioxide  of  Bismuth  (2Bi-f-3O.  160)  is  formed  by  fusing  potassa 
with  the  protoxide  of  bismuth.  It  is  a  brown,  heavy  powder,  little  dis- 
posed to  unite  with  acids,  or  alkalies. 

Chloride  of  Bismuth  (Bi-j-Cl.  106.42)  is  formed  by  the  spontaneous 
combustion  of  bismuth  in  chlorine  gas,  formerly  called  butter  of  bismuth. 
It  is  of  a  grayish-white  color,  and  granular  text  are. 

Bromide  of  Bismuth.     Bi  -f-  Br.  71  -f  78.4  =  149.4. 

Sulphuret  of  Bismuth  (Bi-j-S.  87.1)  is  found  native. 


TITANIUM.    Symb.  Ti.    Equiv.  24.3.     Sp.  gr.  5  3. 

Titanium  was  first  noticed  by  Mr.  Gregor,  of  Cornwall. 
Klaproth  gave  it  the  name  of  titanium,  after  the  Titans  of 
ancient  fable.  But  its  properties  were  determined  by  Wol- 
laston,  in  1822,  who  found  it  in  the  slag  of  an  iron-smelting 
furnace  in  South  Wales. 

Properties.  Its  color  is  red,  resembling  copper.  It  exists 
in  small  cubes,  which  are  so  hard  as  to  scratch  rock-crystal, 
and  very  infusible.  It  generally  contains  traces  of  iron. 
The  pure  metal  is  obtained  by  heating  the  chloride  with  am- 
monia in  a  glass  tube,  when  it  appears  in  the  form  of  a  deep 
blue  colored  powder,  which  is  apt  to  take  fire,  if  exposed  to 
the  air  when  warm. 

Compounds  of  Titanium. 

Oxide  of  Titanium  (Ti  -f-  O.  32.3)  is  obtained  by  exposing  titanic  acid 
to  a  strong  heat  in  a  black-lead  crucible.  It  is  of  a  purple  color. 

Titanic  Acid,  (Ti-f-2O.  40.3,)  also  called  peroxide  of  titanium,  exists 
in  the  minerals  anntase  and  rutile.  from  which  the  acid  is  obtained  by 
the  aid  of  heat  and  hydrosulplmric  acid  gas.* 

*  For  processes,  see  Turner's  Elements. 


268  Met  ah.  —  Tellurium. 

Properties.  Titanic  acid  is  of  a  white  color;  very  infusi- 
ble, and  when  once  ignited,  insoluble  in  acids,  excq>t  in  the 
hydrochloric.  It  is  a  feeble  acid,  resembling  the  silicic.  If 
it  is  ignited  with  potassa,  and  dissolved  in  hydrochloric  acid, 
a  solution  of  gall-nuts  will  produce  an  orange-red  color,  which 
is  very  characteristic  of  titanic  acid. 

Bichloride  of  Titanium  (Ti  +  2Cl.  95.14)  was  discovered  in  1824,  by 
Mr.  George,  of  Leeds,  by  transmitting  dry  chlorine  gas  ovi-r  titanium 
at  a  low  red  heat. 

Properties.  A  transparent,  colorless  liquid,  which  boils 
at  212°.  The  density  of  its  vapor  is  6.615;  combines  with 
water  with  explosive  violence  from  the  evolution  of  intm  • 
heat ;  on  exposure  to  the  atmosphere,  it  emits  dense  white 
fumes,  of  a  pungent  odor,  similar  to  chlorine. 

Bisulphuret  of  Titanium.  Ti  +  2S.  Eq.  24.3  +  32.2  = 
56.5. 


TELLURIUM.    Symb.  Te.     Equiv.  64.2.    Sp.gr.  6.115. 

Tellurium  is  a  rare  metal,  found  only  in  small  quantities  in 
Transylvania  and  Connecticut.  It  was  first  noticed  by  Miil- 
ler,  in  1782,  but  its  existence  was  more  fully  established  in 
1798,  by  Klaproth,  who  called  it  tellurium,  from  tellus,  the 
earth.  It  is  found  chiefly  in  combination  with  gold  and 
silver. 

Properties.  It  is  ~a  brittle  metal,  of  a  bright  gray  color ; 
very  infusible  and  volatile.  Heated  in  the  air,  it  burns  with 
a  sky-blue  flame,  edged  with  greeji;  placed  upon  charcoal 
before  the  blowpipe,  it  inflames  with  violence,  and  flies  en- 
tirely off  in  gray  smoke,  having  a  peculiarly  nauseous  smell. 

Compounds  of  Tellurium. 

Tellurous  Acid,  (Te  +  2O.  80.2,)  also  called  oxide  of  tel- 
lurium, is  generated  by  the  action  of  nitric  acid  on  tellurium. 
It  is  a  white,  granular  powder,  resembling  in  many  of  its 
properties  the  titanic,  and  several  other  feeble  acids.  Its 
aqueous  solution  reddens  litmus  paper. 

The  other  compounds  are  the  Telluric  Jciil,  (Te  -f-  3O.  RS.2;)  Chlo- 
ride of  Tellurium,  (Te  +  Cl.  99.G2 ;)  Bichloride,  (Te  +  2C1.  135.04;) 
Bisulphuret.  (Te4-2S.  96.4:)  Persulphurtt  and  Hudrotelluric  rfcid, 
(Te-f  H.  65.2.) 


Copper. 


COPPER.    Symb.Cu.     Equiv.31.6.     Sp.  gr.  8.895. 

Copper,  from  cuprum,  a  name  derived  from  the  island 
Cyprus,  has  been  known  from  the  remotest  ages. 

Natural  History.  It  is  found  native,  and  in  combination 
with  other  substances,  especially  with  sulphur.  The  copper 
of  commerce  is  chiefly  obtained  from  the  native  sulphurets. 
It  exists  in  great  abundance  in  Cornwall,  and  other  parts  of 
Europe,  in  Liberia,  and  in  America. 

Schoplcraft  found  a  mass  of  native  copper  about  thirty 
miles  from  Lake  Superior,  which  weighs,  by  estimation, 
2000  Ibs. 

Process.  It  may  be  obtained  perfectly  pure,  by  dissolving 
the  copper  of  commerce  in  hydrochloric  acid,  diluting  the 
solution,  arid  immersing  in  it  a  clean  plate  of  iron,  upon 
which  the  copper  will  be  precipitated. 

Properties.  Copper  is  distinguished  from  all  other  metals, 
except  titanium,  by  its  red  color.  It  is  very  ductile  and 
malleable;  melts  at  1996°  Fahr. ;  burns  before  the  com- 
pound blowpipe  with  a  beautiful  green  flame,  and  if  a  fused 
globule  be  thrown  into  a  glass  jar,  two  feet  high,  filled  with 
water,  it  will  pass  in  full  ignition  to  the  bottom,  and  remain 
some  time  at  a  red  heat. 

Uses.  Copper  is  one  of  the  most  useful  metals,  being  em- 
ployed extensively  in  most  of  the  arts  of  life. 

Compounds  of  Copper. 

Red,  or  Dioxide  of  Copper  (2Cu  +  O.  71.2)  is  found 
native  in  octohedra)  crystals. 

Process.  It  may  be  prepared  artificially,  by  heating,  in  a 
covered  crucible,  a  mixture  of  31.6  parts  of  copper-filings 
with  39.6  of  the  black  oxide. 

Properties.     It  resembles  copper  in  color ;  sp.  gr.  6.093 ; 
soluble  in  ammonia,  and   the  solution   is   colorless,   but   it 
absorbs  oxygen  on  exposure  to  the  air,    which  produces  a 
blue  color,  owing  to  the  formation  of  the  black  oxide. 
23* 


270  Metals.  —  Alloys  of  Copper. 

Black,  or  Protoxide  of  Copper.  Cu  +  O.  39.6.  This  is  the  copper- 
black  of  mineralogists,  and  is  formed  by  the  spontaneous  oxidation  of 
other  ores  of  copper. 

Properties.  It  varies  from  a  dark  brown  to  a  bluish-black 
color,  according  to  the  mode  of  formation;  combines  with 
most  of  the  acids,  and  its  salts  have  a  green  or  blue  tint.  It 
forms  with  ammonia  a  deep  blue  solution,  which  distinguishes 
it  from  all  other  substances.  The  salts  of  the  protoxide  of 
copper  are  mostly  distinguished  by  their  color.  Metallic 
copper  is  separated  from  the  salts  by  a  rod  of  iron-  or  zinc. 

Binoxide  of  Copper.     Cu  +  2O.  31  6  +  16  =  47.C. 

Dichlnridc  of  Copper  (2Cu  +  Cl.  98.02)  is  formed  by  the  spontane- 
ous combustion  of  copper-filings  in  chlorine  gas.  It  is  of  various  colors, 
white,  yellow,  and  dark  brown,  according  to  the  mode  ofpreparation  ; 
soluble  in  hydrochloric  acid,  but  not  in  water. 

Chloride  of  Capper;  Cu  -f-  Cl.  67.02.  Diniodide.  of  Copper ;  2Cu  -f- 
I.  63.2-4-120.3  =  189.5.  Sitlphuret  of  Copper  (ru  +  S.  47.7)  is  a 
constituent  of  copper  pyrites,  in  which  it  is  combined  with  protnsul- 
plmrt't  of  iron.  Triphosphuret  of  Copper;  3Cu-f-P.  110.5.  Subse- 
iiuiphosphuret ;  3Cu-r-2P.  126.2.  Cyanurel  of  Copper;  Cu-f-Cy. 
57.99.  Disulphocyanuret  of  Copper;  Cu  +  CyS'.  03.2 -f-  (2G.:t9  + 
32.  2)  ==  121.79.  —  (See  Turner's  Elements,  p.  389.) 

Tests.  The  best  mode  of  detecting  copper  in  mixed  liquids  is  the 
hydrosulphuric  acid.  The  sulphuret,  after  being  collected,  and  h<  at. d 
to  redness  in  order  to  char  organic  matter,  should  be  placed  on  a  pn  •  .- 
of  porcelain,  and  be  digested  in  a  few  drops  of  nitric  acid  ;  sulplmtr  «(' 
the  protoxide  of  copper  is  formed,  which,  when  evaporated  to  dryness, 
strikes  the  characteristic  blue  tint  on  the  addition  of  ammonia.  —  T. 

Alloys.  The  alloys  of  copper  are  very  important  and  use- 
ful substances. 

Brass  is  an  alloy  of  copper  and  zinc.  The  best  bra-- 
consists of  four  parts  of  copper  to  one  of  zinc.  Tutum" 
contains  in  addition  a  little  iron.  Tombac,  Dutch  Gold,  Si- 
milor,  Prince  Rupert's  Metal,  arid  Pinchbeck,  contain  more 
copper  than  brass.  Bell-metal  and  Bronze  are  alloys  of  cop- 
per and  tin.  The  best  proportion  for  bell-metal  is  3  parts 
of  copper  to  1  of  tin;  for  bronze,  8  to  12  of  tin  to  100  of 
copper.  In  these  alloys,  according  to  Dalton,  the  elements 
combine  in  definite  proportions. 

Poisonous  Properties  of  Copper.  Copper  vessels  used  for 
culinary  purposes  should  be  coated  with  tin,  as  the  oxide  is 
poisonous.  This  is  done  by  making  the  surface  of  the  copper 
bright,  rubbing  over  a  little  sal-ammoniac  to  prevent  oxidation, 
and  then  heating  the  vessel  and  rubbing  it  with  rosin  and  tin. 


Lead.  271 

LEAD.     Symb.  Pb.     Equiv.  103.6.     Sp.  gr.   11.352. 

Lead  was  well  known  to  the  ancients.  It  is  rarely  found 
native,  but  its  ores  are  abundant,  the  most  important  of  which 
is  the  sulphuret  or  galena,  from  which  the  pure  metal  is 
chiefly  obtained.*  Berzelius  obtained  the  metal  perfectly 
pure  by  heating  the  pure  nitrate  of  lead,  mixed  with  charcoal, 
in  a  Hessian  crucible. 

Properties.  The  properties  of  lead  are  generally  well 
known.  It  is  of  a  bluish-white  color,  soft,  malleable,  and 
ductile;  fuses  at  612°,  and  by  slow  cooling,  crystallizes  in 
octohedra.  The  proper  solvent  of  lead  is  nitric  acid. 

Compounds  of  Lead. 

Protoxide  of  Lead  (Pb  +  O.  111.6.  Sp.  gr.  9.4214)  is 
prepared  by  heating  the  rnetal  to  a  high  temperature,  and  col- 
lecting the  gray  film  which  forms  on  the  surface.  This  is 
exposed  to  heat  in  open  vessels,  until  it  acquires  a  uniform 
yellow  color,  and  constitutes  the  massicot,  and  when  partially 
fused,  the  litharge  of  commerce.  This  is  always  mixed  with 
the  red  oxide  ;  it  is  obtained  perfectly  pure  by  adding  ammo- 
nia in  excess  to  the  nitrate  in  solution,  washing  the  precipi- 
tate in  cold  water,  and,  when  dry,  heating  it  to  redness  foiuan 
hour  in  a  platinum  crucible. 

Properties.  Its  color  is  red  when  hot,  but  acquires  a  rich 
lemon-yellow  when  cold  ;  fuses  at  a  bright  red  heat,  and,  after 
fusion,  has  a  highly-foliated  texture ;  insoluble,  in  water ;  unites 
with  acids,  and  forms  the  base  for  all'the  salts  of  lead. 

It  'is  precipitated  from  its  solutions  by  pure  alkalies  as  a 

^_  _J> i i 

*  Process.  The  ore,  in  the  state  of  coarse  powder,  is  heated  in  a 
reverberatory  furnace,  when  part  of  it  is  oxidized,  yielding  sulphate  of 
protoxide  of  lead,  sulphuric  acid  which  is  evolved,  and  free  oxide  of 
lead.  These  oxidized  portions  then  re-act  on  sulphuret  of  lead,  by  the 
re-action  of  2  equivalents  of  oxide  of  lead,  and  1  of  the  sulphuret; 
3  equivalents  of  oxide  of  lead  and  1  of  sulphuric  acid  result, 
while  1  equivalent  of  the  sulphuret  and  1  of  the  sulphate  mutually 
decompose  each  other,  giving  rise  to  2  equivalents  of  sulphurous  acid, 
and  2  of  metallic  lead.  The  lead  of  commerce  commonly  contains 
silver,  iron,  and  copper.  —  T. 


272  Met  ok.  —  Lead 

white  hydrate,  which  is  re-dissolved  by  potassa  in  excess  ,  asr 
a  white  carbonate,  which  is  the  well-known  pigment  white 
Irafl,  by  alkaline  carbonates  ;  as  a  white  sulphate,  by  soluble 
sulphates;  as  a  dark  brown  sulphuret  by  hydrosulphuric  acid  ; 
and  as  a  yellow  iodide  of  lead,  by  hydriodic  acid,  or  iodide 
of  potassium.  —  T. 

Metallic  Lead  is  separated  from  the  salts  of  the  protoxide 
by  iron  or  zinc. 

Erjt.  In  a  solution  of  1  part  of  acetate  of  lead  in  24  parts  of  water, 
contained  in  a  glass  bottle,  suspend  a  piece  of  zinc  by  a  tlm-ad.  Tin- 
lead  will  be  deposited  upon  the  zinc  in  a  form  resembling  a  tree  —  a 
peculiar  appearance,  called  arbor  Saturni. 

Uses.  Protoxide  of  lead  enters  into  the  composition  of 
flint-glass,  and  is  employed  for  glazing  earthen-ware  and  por- 
celain. 


Peroxide  of  Lead  (Pb  +  2O.  119.G)  is  formed  by  the  action  of  nitric 
acid  upon  the  red  oxide,  or  minium  of  commerce.  It  is  of  a  puce  color, 
insoluble  in  water,  and  resolved  by  strong  oiygen  acids  into  a  salt  of 
the  protoxide  and  oxygen  gas. 

Red  O/idr  of  Lead  (3  Pb  +  4O.  342.8)  is  prepared  by 
heating  lead  in  the  air  nearly  to  the  point  effusion,  by  which 
it  is  oxidized.  It  is  then  exposed  to  a  temperature  of  <>(M)' 
or  700°,  while  a  current  of  air  passes  across  its  surface.  It 
slowly  absorbs  oxygen,  and  is  converted  into  the  mhihnn  of 
commerce.  It  is  employed  as  a  pigment,  and  in  the  manu- 
facture of  flint-glass,  but  does  not  unite  with  acids  and  form 
salts. 

Chloride  of  Lead  (Pb-f-Cl.  130.02)  is  obtained  by  adding  hydro- 
chloric acid  to  a  solution  of  acetate  or  nitrate  of  lead.  It  is  sometimes 
called  horn  lead  ;  dissolved  in  hot  water,  it  appears,  on  cooling,  in 
small,  acicular,  anhydrous  crystals,  of  a  white  color. 

Iodide  of  Lead;  Pb-fl.  229.9.  Bromide  of  Lead;  Pb  +  Br.  182. 
Fluoride  of  Lead  ;  Pb  +  F.  122.28.  Sulpkuret  of  Lead  ;  Pb  -f-  8.  11  9.7. 
Phosphvret  of  Lead  and  Carburet  of  Lead,  composition  uncertain.  Cy- 
anuret  of  Lead;  Pb-f-  Cy.  129.99.  —  (See.  Turner's  Elements,  p.  393.) 

The  salts  of  lead  are  generally  poisonous,  of  which  the 
carbonate  is  the  most  virulent. 

Alloys  of  Lead.  Common  pncter  is  an  alloy  of  20  parts 
of  lead  and  80  of  tin.  Fine  solder  consists  of  1  part  of  lead 
and  2  of  tin,  and  is  employed  for  tinning  copper.  Coarse 
solder  contains  one  fourth  of  tin,  and  is  used  by  plumbers. 
Pot  metal  is  an  alloy  of  lead  and  copper. 


Mi-miry.  273 

X 

SECT.  3.     METALS,  THE  OXIDES  OF  WHICH  ARE  REDUCED 
TO  THE  METALLIC  STATE  BY  A  RED  HEAT. 

MERCURY,  or  QUICKSILVER. 

Symb.  Hg.     Equiv.  202.     Sp.  gr.  13.568. 

Mercury  was  well  known  to  the  ancients.  Its  principal 
ore  is  the  sulphuret  or  native  cinnabar,  from  which  it  is 
separated  by  distillation  with  quick  lime,  or  iron-filings. 

Properties.  Mercury  is  the  only  metal  which  retains  its 
liquid  form  at  common  temperatures.  It  is  of  a  tin-white 
color,  and  strong  metallic  lustre ;  boils  at  662°  Fahr.,  and 
congeals  at  40°  below  zero,  in  which  state  it  is  malleable, 
and  has  an  increased  specific  gravity  15.612.  It  is  not  tar- 
nished by  exposure  to  cold,  moist  air,  unless  it  contain  other 
metals.  It  is  sometimes  adulterated  with  an  alloy  of  lead  and 
bismuth,  which  renders  it  less  fluid  and  volatile,  leaving  a 
residuum  when  boiled  in  a  silver  spoon. 

Mercury  is  not  acted  upon  by  any  of  the  acids  except  the 
sulphuric  and  nitric. 

It  is  used  for  collecting  those  gases  which  are  absorbed  by 
water;  also  for  barometers,  thermometers,  and  for  forming 
connections  in  voltaic  circles. 

Compounds  of  Mercury. 

Protoxide  of  Mercury  (Hg-j-O.  210)  is  prepared  by 
mixing  calomel  with  pure  potassa  in  excess  in  a  mortar,  and 
stirring  it  briskly  to  effect  a  rapid  decomposition.  The  pro- 
toxide is  then  washed  in  cold  water,  and  left  to  dry  in  a  dark 
place. 

Properties.  It  is  a  black  powder,  insoluble  in  water,  com- 
bining with  acids,  and  bui  feebly  with  alkalies.  The  alkalies 
precipitate  it  from  the  solution  of  its  salts,  as  a  black  protox- 
ide. The  best  test  of  its  presence  is  the  hydrosulphuric 
acid,  by  which  it  is  thrown  down  as  a  black  protosulphuret. 


274  Metals.  —  Mtrrury. 

Binoxide  of  Mercury  (Hg+-2O.  218)  is  commonly 
known  by  the  name  of  red  precipitate.* 

Process.  Peroxide  of  mercury  may  be  prepared  by  dissolving  mer- 
cury in  nitric  acid,  and  exposing  the  nitrate  thus  formed  to  a  fempera- 
ture  just  sufficient  to  expel  the  whole  of  the  nitric  acid.  It  may  aU<>  In- 
formed by  exposing  mercury  in  a  matrass,  with  a  long  tulie,  to  tin- 
agency  of  heat  and  air,  for  the  space  of  three  or  font  weeKs. 

Properties.  It  exists  in  shining,  crystalline  scales,  nearly 
black  when  hot,  and  red  when  cold;  slightly  soluble  ::i 
water.  The  solution  has  an  acrid,  metallic  taste,  and  is  poi- 
sonous. 

This  oxide  is  separated  from  all  acids  by  the  carbonated 
fixed  alkalies,  and  is  reduced  to  the  metallic  state  by  copper. 

Protochloride  of  Mercury  (Hg-{-Cl.  237.42)  is  common- 
ly called  calomel,  and  was  first  mentioned  in  the  seventeenth 
century,  by  Crollius. 

Process.  It  may  be  obtained  by  bringing  chlorine  gas  in  contact 
with  mercury,  but  it  is  more  commonly  prepared  by  sublimation.  This 
is  done  by  mixing  1  equiv.  of  the  bichloride  with  1  eqmv.  of  mercury, 
until  the  metallic  globules  entirely  disappear,  and  then  subliming. 
To  purify  it  from  corrosive  sublimate,  which  is  always  mixed  \\  itli  it, 
when  first  prepared,  it  must  be  reduced  to  powder,  and  well  washed, 
\\li.n  it  will  be  fitted  for  chemical  or  medical  purposes.  The  proto- 
chloride  is  also  found  native,  and  called  horn  quicksilver. 

Properties.  When  obtained  by  this  process,  calomel  ex- 
ists in  semi-transparent,  crystalline  cakes,  of  a  yellow  color 
when  warn),  but  white  when  cold  ;  sublimes  a  little  below 
a  red  heat,  and  n  part  of  it  is  resolved  into  mercury,  and 
the  bichloride.  It  is  insoluble  in  water,  and  is  tlecomp 
by  the  pure  alkalies. 

Used  extensively  for  medical  purposes;  acts  powerfully 
upon  the  glandular  system. 

Bichloride  of  Mercury  (Hg-J-2Cl.  272.84)  is  formed  by  heating  mer- 
cury in  chlorine  gas.  During  the  process,  the  metal  burns  with  a  pale 
red  flame.  It  is  prepared  fur  mediea!  purposes  hy  subliming  a  mixture 
of  bisulphate  of  the  peroxide  of  m.  icury  with  chloride  of  sodium,  or 
sea-suit. 


.  Bichloride  of  mercury,  commonly  called  «»•- 
rtttirt  HssVtffnaftj  is  ;\  most  virulent  poi<on.  It  is  white,  semi- 
transparent,  and  crystalline  in  its  texture';  taste  acrid  and 
nauseous;  more  soluble  in  alcohol  than  in  water;  sp.  gr.  -~>.M. 
It  sublimes  in  the  form  of  a  dense,  white  vapor,  when  heated, 

*  This  is  t!.e  hydrargyri  oxidum  rubrum  of  the  pharmacopolist. 


Compounds  of  Mercury.  275 

powerfully  affecting  the  mouth  and  nose ;  soluble  in  hydro- 
chloric, nitric,  and  sulphuric  acids,  and  is  decomposed  by 
the  alkalies,  and  several  of  the  metals.* 

Tests.  Place  a  drop  of  the  suspected  liquid  on  polished  gold,  and 
touch  the  moistened  surface  with  the  point  of  a  penknife ;  the  part 
touched  will  instantly  become  white,  owing  to  the  formation  of  an 
amalgam  of  gold". 

Some  animal  and  vegetable  substances  convert  the  bichloride  into 
calomel ;  the  best  is  albumen,  made  by  mixing  the  white  of  an  egg  in 
water  •,  hence  the  white  of  an  egg  is  an  antidote  to  poisoning  by  cor- 
rosive sublimate. 

Protosulphutet  of  Mercury.     Hg  +  S.  218.1. 

Bisulpkurct  of  Mercury  (fl<r-f-2S.  234.2)  maybe  formed  by  fusing 
sulphur  with  six  times  its  weight  of  mercury,  and  subliming  in  close 
vessels. 

Properties.  When  thus  obtained,  it  has  a  red  color,  and 
is  known  by  the  name  tf factitious  cinnabar.  When  reduced 
to  powder,  its  tint  is  greatly  improved,  and  constitutes  the 
well  known  pigment,  vermilion.  The  native  cinnabar  is  a 
bisulphurct,  and  is  the  principal  ore  of  mercury. 

JEthiops  Mini-ral  is  a  mixture  of  sulphur  and  the  bisul- 
phuret,  and  may  be  formed  by  triturating  equal  parts  of  sul- 
phur and  mercury,  until  the  globules  of  mercury  disappear. 

Bicyannrct  of  Mercury  (Hg~h2Cy,  228.39)  is  prepared  by  boiling  a 
solution  of  Prussian  blue  with  an  equal  weight  ot  peroxide  of  mercury 
in  powder,  until  the  blue  color  of  the  pigment  entirely  disappears. 
The  solution,  on  evaporation,  yields  quadrnngular  prisms  of  bicyanuret 
t>f  mercury.  It  is  colorless,  inodorous,  and  highly  poisonous. 

Amalgams.  Mercury  combines  with  most  of  the  metals, 
and  forms  a  class  of  compounds  called  amalgams.  An 
amalgam  of  one  part  of  potassium  and  seventy  of  mercury 
is  hard  and  brittle  ;  on  adding  mercury  to  the  liquid  alloy 
of  potassium  and  sodium,  solidification  and  combustion 
rnsue.  Two  parts  of  mercury,  one  of  bismuth,  and  one  of 
lead  form  a  liquid  amalgam,  from  which  cubic  crystals  of 
bismuth  are  slowly  formed.  The  combination  of  mercury 
with  those  metals  which  are  not  easily  oxidized,  enables 
them  to  combine  with  oxygen ;  hence  gold  and  silver,  in 
combination  with  mercury,  are  easily  oxidized  by  heat  and 
air.  With  tin,  it  forms  an  amalgam  for  coating  mirrors. 

*  Pr  of  iodide  of  mercury  ;  Hg  +  I.  328.3.  Scsqu  iodide;  Hg2!3.  782.9. 
Biniodidc ;  Hgl*.  454.6.'  Protobromide ;  HgBr.  280.4.  Bibromidc  of 
mercury;  Hg-f-2Br.  358.8.  lodurctcd  bichloride  of  mercury;  20HjrCla 
4- 1.  5583. 1 .  lodobichloride  of  mercury  ;  40HgCl2  +  Hgl*.  1 1368.2. 


276  Metals.  —  Silver. 


SILVER*    Symb.  Ag.    Equiv.  108.     Sp.  gr.  10.51. 

Silver  has  been  known  from  the  earliest  ages.  It  is  found 
native,  and  in  combination  with  other  substances.  The 
native  silver  occurs  in  octohedral  or  cubic  crystals,  seldom 
perfectly  pure ;  it  is  generally  found  in  primitive  formations. 
Peru  and  Mexico  contain  the  richest  mines  of  native  silver 
which  are  known. 

Preparation.  Pure  silver  may  be  obtained  from  standard 
silver,  by  dissolving  it  in  nitric  acid  and  introducing  a  clean 
piece  of  copper.  The  metal  will  be  precipitated  upon  the 
copper;  this  is  then  to  be  washed  in  pure  water,  and  di- 
gested in  ammonia  to  remove  the  copper.  A  better  pro- 
cess is  to  decompose  the  chloride  of  silver  by  carbonate  of 
potassa. 

Silver  is  often  obtained  from  the  argentiferous  sulphurct 
of  lead,  by  a  process  called  eifpeJZdffM.T  Some  of  the  orei 
are  also  reduced  by  amalgamation  with  mercury,  and  the 
mercury  expelled  by  heat. 

Properties.  Silver  has  the  clearest  white  color  of  all  the 
metals.  Its  lustre,  when  polished,  is  surpassed  only  by  pol- 
ished steel ;  so  malleable  that  it  may  be  extended  into  leaves 
less  than  a  ten  thousandth  of  an  inch  in  thickness,  and  so 
ductile  that  it  may  be  drawn  into  wire  finer  than  the  human 
hair.  It  fuses  at  1873°  Fahr.,  and  appears  extremely  brilliant. 

*  Lat.  argentum. 

t  This  process  is  conducted  in  the  following  manner  :  — The  lead  is 
kept  at  a  red  heat,  in  a  flat  furnace,  with  a  draught  of  air  playing  on 
its  surface.  The  lead  is  thus  rapidly  oxidized,  while  the  silver  is  un- 
affected. As  fast  as  the  oxide  is  formed,  it  melts  and  runs  off  through 
an  aperture  in  the  sides  of  the  furnace;  so  that,  in  the  end.  the  Ir.-uJ  is 
all  removed.  The  button  of  silver  which  remains  is  then  melted  in  a 
small  furnace  resting  on  a  porous  earthen  dish  made  with  bone  ashes, 
called  a  cupel,  the.  porosity  of  which  is  so  great  that  it  absorbs  any  por- 
tions of  litharge  which  may  remain  on  the  silver.  The  ciijtrl  is  prepared 
by  driving  pounded  bone  ashes  into  a  small  brass  mould  by  means  of 
a  pestle.  It  should  then  be  removed  and  dried  on  paper.  The  cupel 
is  then  placed  in  a  muffle,  which  is  made  of  clay,  arched  above,  and 
closed  on  all  sides  except  the  front.  The  whole  is  then  placed  in  a 
cupelling  furnace ,  which  has  an  opening  in  one  of  its  sides  to  receive 
the  muffle.  This  is  a  very  important  process,  and  much  used  by  re- 
finers and  assayers,  in  the  analysis  of  alloyed  silver- 


Compounds  of  Silver  277 

It  is  not  oxidized  by  air  or  moisture,  but  is  tarnished  by 
sulphurous  vapors,  which  act  slowly  upon  it;  it  burns  with 
a  fine  green  light,  and  throws  off  fumes  of  oxide  when  ex- 
posed to  the  action  of  voltaic  currents.  None  of  the  pure 
acids  act  upon  it  but  the  sulphuric  and  nitric;  the  latter  is 
its  proper  solvent,  with  which  it  forms  the  nitrate  which, 
after  fusion,  is  the  lunar  caustic. 

Use.  Silver  is  one  of  the  precious  metals,  and  is  used  as 
a  coin,  and  for  various  purposes  of  art. 

Oxide  of  Silver  (Ag-fO  or  AgO.  1 16)  is  best  formed  by 
mixing  a  solution  of  pure  baryta  with  the  nitrate  dissolved 
in  water  ;  it  is  of  a  brown  color,  insoluble  in  water,  and 
easily  reduced  by  a  red  heat. 

Fulminating  Silver  is  a  compound  of  oxide  of  silver  and  ammonia. 

Process.  Precipitate  nitrate  of  silver  by  lime  water ;  and,  after  wash- 
ing and  drying  the  precipitate,  put  it  into  a  vessel  of  pure  ammonia 
for  twelve  hours;  a  black  powder  will  be  thrown  down,  which,  when 
carefully  dried,  explodes  violently  by  the  gentlest  heat,  or  by  slight 
friction.  Great  care  should  be  taken  in  its  preparation,  and  it  should 
be  preserved  in  small  quantities  in  paper  boxes. 

By  heating  the  solution,  a  more  dangerous  compound  is  formed. 

A  compound  similar  to  the  above,  but  .less  dangerous,  is  formed  by 
dissolving  silver  in  nitric  acid,  and  adding  to  the  solution  successive 
portions  of  alcohol.  This  substance  is  used  in  the  preparation  of  small 
balls  called  torpedoes. 

Chloride  of  Silver  (Ag  +  Cl.  143.42)  is  the  horn  silver 
of  mineralogists. 

Process.  It  is  formed  by  mixing  hydrochloric  acid  with 
a  solution  of  oxide  of  silver.  When  first  precipitated,  it  is 
white,  but  becomes  almost  black  by  exposure  to  the  solar 
rays;  insoluble  in  water,  but  very  soluble  in  ammonia,  by 
which  it  is  usually  distinguished  from  other  chlorides.  It  is 
often  employed  in  analysis  as  the  means  of  ascertaining  the 
amount  of  chlorine  present  in  various  compounds. 

Iodide  of  Silver  (Ag-j-I-  234.3)  is  a  greenish-yellow  substance. 

Sulphuret  of  Silver.  Ag -f- S.  124.1.  This  is  the  silvrr  gl.anc&  of 
mineralogists.  Silver  has  a  strong  affinity  for  sulphur.  Qn  passing  a 
current  of  hydrosulphuric  acid  gas  through  a  solution  of  lunar  caustic, 
a  dark  brown  precipitate  subsides,  which  is  a  sulphuret  of  silver. 

Cyanuret  of  Silver  (Ag-f-  Cy.  134.39)  is  a  white,  curdy  substance. 

Alloys  of  Silver.     Silver  is  alloyed  with  most  of  the  metals. 
With  steel,  it  forms  an  alloy  used  in  cutlery ;  with  copper, 
24 


278  Metals.  —  Gold. 

it  forms  the  silver  plate  and  coin,*  which  is  the  most  useful 
of  its  alloys ;  with  mercury,  it  forms  an  amalgam,  sometimes 
employed  for  plating  copper.  Thermometer  scales  and 
clock  dials  are  usually  silvered  by  an  alloy  of  chloride  of 
silver,  chalk,  and  pearlashes. 

GOLD.\    Syrab.  Au.    Equiv.  199.2.    Sp.  gr.  19.257. 

Gold  Was  known  to  the  ancients,  and  has  always  been 
highly  valued,  as  the  most  precious  of  the  metals. 

.  Natural  History.^  Gold  occurs  native,  alloyed  with  a  little 
silver  or  copper.  It  crystallizes  in  cubes  and  octohedra ;  it 
is  found  in  large  quantities  in  alluvial  soils,  and  in  the  beds 
of  certain  rivers,  especially  on  the  western  coasts  of  Africa 
and  Peru,  in  Brazil  and  Mexico,  in  Europe  and  the  United 
States.f 

Process.  Gold  is  generally  separated  by  amalgamation 
and  cupellation ;  but  the  best  mode  is  to  fuse  the  gold  with 
silver,  so  that  the  latter  shall  constitute  J  of  the  mass  ;  nitric 
acid  will  dissolve  the  silver,  and  leave  the  gold.  This  process 
is  called  quartation. 

To  obtain  gold  perfectly  pure,  dissolve  standard  gold  in 
nitrohydrochloric  acid;  evaporate  the  solution  to  drymv-s, 
re-dissolve  it  in  distilled  water,  filter,  and  add  to  the  solu- 
tion sulphate  of  the  protoxide  of  iron  ;  a  black  powder  falls, 
which,  when  washed  in  dilute  hydrochloric  acid  and  distilled 
water,  yields,  on  fusion,  a  button  of  pure  gold. 

Properties.  Gold  is  distinguished  from  all  other  metals 
by  its  yellow  color;  it  exceeds  all  others  in  ductility  and 
malleability ;  it  may  be  beaten  into  leaves  not  exceeding 
SFsWtT  °f  an  m°h  m  thickness  ;  it  is  very  flexible  and  soft ; 
fuses  at  2016°  Daniell,  and  appears  of  a  brilliant  green  color. 

*  The  standard  silver  of  Great  Britain  contains  11^-  of  pure  silver, 
and  £$.  of  copper ;  that  of  the  United  States,  1  part  by  weight  of 
copper,  and  9  of  silver.  The  dollar  weighs  4124-  grs.,  and  the  dime 
41±  grs. 

t  Lat.  aurum. 

t  The  gold  from  all  the  mines  in  the  United  States,  in  1836,  amounted 
to  467,000  dollars,  148,100  dollars  of  which  were  from  North  Carolina. 


Compounds  of  Gold.  279 

It  is  not  easily  oxidized,  even  in  the  state  of  fusion ;  but,  on 
subjecting  a  fine  wire  to  an  electric  discharge,  a  purple 
powder  is  produced,  which  is  probably  an  oxide;  it  is  readily 
dissolved  by  nitrohydrochloric  acid. 

Protoxide  of  Gold  (Au+O.  207.3)  is  formed  by  adding 
a  cold  solution  of  potassa  to  the  protochloride;  a  precipitate 
falls,  of  a  green  color,  which  changes  spontaneously  into  me- 
tallic gold  and  teroxide. 

Binoxide  of  Gold  (Au-f-2O.  215.2)  is  formed  by  the  combustion  of 
gold. 

Teroxide  of  Gold  (Au  +  3O.  223.2)  is  the  only  well- 
known  oxide  of  gold. 

Process.  Dissolve  1  part  of  gold  in  the  usual  way,  render  it  quite 
neutral  by  evaporation,  and  re-dissolve  in  12  parts  of  water;  to 
the  solution  add  1  part  of  the  carbonate  of  potassa,  dissolved  in 
twice  its  weight  of  water,  and  digest  at  about  170° ;  carbonic  acid 
gradually  escapes,  and  the  hydrated  teroxide,  of  a  brownish-red 
color,  subsides.  After  being  well  washed,  it  is  dissolved  in  colorless 
nitric  acid  of  sp.  gr.  1.4,  and  the  solution  decomposed  by  admixture 
with  water. 

The  hydrated  teroxide  is  thus  obtained  quite  pure,  and  is  rendered 
anhydrous  by  a  temperature  of  212°  Fahr.  —  T. 

Properties.  The  hydrate  is  yellow,  but  the  anhydrous 
teroxide  is  nearly  black,  insoluble  in  water,  and  completely 
decomposed  by  solar  light,  or  a  red  heat.  With  alkalies  it 
acts  the  part  of  a  weak  acid,  and  was  called  by  Pelletier 
auric  acid.  When  the  teroxide  is  kept  in  ammonia  for  the 
space  of  a  day,  a  detonating  compound  of  a  deep  olive  color 
is  formed.  It  is  composed  of  1  equiv.  of  gold,  2  of  nitro- 
gen, 6  of  hydrogen,  and  3  of  oxygen. 

The  Fulminating  Gold  is  a  similar  compound. 

Process.  A-ld  pure  liquid  ammonia  to  the  dilute  chloride. 
The  precipitate  which  is  formed  will  be  re-dissolved  if  too 
much  alkali  is  used;  filter  the  liquid,  and  wash  the  sediment 
several  times  in  warm  water ;  dry  it  by  exposure  to  the  air, 
and  preserve  it  in  small  paper  boxes.  • 

Exp.  Hold,  on  the  point  of  a  knife,  a  small  portion  of  the  powder 
over  the  flame  of  a  spirit  lamp,  and  it  will  detonate  violently. 

Exp.  Place  two  or  three  grains  on  a  sheet  of  copper,  and  explode  it; 
it  will  force  a  hole  through  the  copper ;  a  spark  from  the  electrical 
machine,  or  from  a  flint,  will  not  affect  it ;  but  the  slightest  friction  will 
cause  it  to  explode ;  hence  the  danger  of  forming  it,  or  of  putting  it  up 
in  large  quantities. 


280  Metals.  —  Gold. 

Protochloride  of  Gold.    Au  +  Cl.  234.62. 

Tcrchloride  of  Gold  (Au  +  3Cl.  305.46)  is  obtained  by 
concentrating  a  solution  of  gold,  in  ruby-red  crystals.  This 
is  the  compound  from  which  pure  gold  is  obtained,  and  also 
most  of  the  preparations  of  gold. 

Krp.  When  a  strong  aqueous  solution  of  the  terchlnride  is  shaken 
with  an  equal  volume  of  ether,  two  fluids  result,  the  lighter  of  which 
is  an  ethereal  solution  of  gold. 

Exp.  When  a  piece  ofcharcoal  is  immersed  in  the  aqueous  solution, 
and  exposed  to  the  solar  rays,  it  is  covered  with  metallic  gold. 

/•>/».  Ribbons  are  gilded  by  moistening  them  in  this  solution,  and 
exposing  them  to  a  current  of  hydrogen  gas. 

Exp.  Add  the  protochloride  of  tin  to  a  dilute  aqueous  solution  of 
gold,  and  a  purple-colored  precipitate,  the  purple  of  Cnssius,  is  thrown 
down.  On  fusing  this  powder  with  sand  and  borax,  it  forms  a  purple 
enamel,  which  is  used  for  giving  a  pink  color  to  porcelain.* 

Alloys  of  Gold.  Gold  forms  alloys  with  most  of  the 
metals.  With  tin  it  forms  a  whitish  brittle  alloy.  On 
this  account  the  old  chemists  called  tin  diabolus  metal' 
lorum. 

With  lead,  it  forms  a  very  brittle  alloy.  Even  the  fumes 
of  lead  destroy  the  ductility  of  gold.  With  copper,  it  forms 
the  alloy  used  for  standard  gold  ;  which  is  perfectly  malleable 
and  ductile,  harder  than  pure  gold,  and  resists  wear  better 
than  any  other  alloy,  except  that  of  silver ;  sp.  gr.  17.157. 
The  standard  gold  of  the  United  States  is  an  alloy  of  1  part 
of  an  alloy  of  copper  and  silver,  and  9  parts  of  pure  gold. 
The  British  "sovereign"  is  22  carats  fine,  that  is,  22  parts 
of  pure  gold,  and  2  of  copper  and  silver. 

Water-Gilding.  Mercury  and  gold  combine,  and  form  an 
amalgam  much  employed  in  gilding.  It  is  applied  to  the 
surface  of  silver,  and  the  mercury  driven  off  by  heat. 

Porcelain  is  gilded  with  gold  powder,  obtained  by  de- 
composing the  chloride  of  gold ;  applied  with  a  pencil, 
and  burnished  after  exposure  to  the  heat  of  a  porcelain  fur- 
nace. 


*  Iodides  of  gold  are  formed  by  the  action  of  iodide  of  potassium  on 
the  terchloride  of  gold.  Protiodide  of  gold;  Au  -f-I.  325.5.  Teriodide 
of  gold;  Au  -f  31.  578.1.  Tersutphuret  of  gold  ;  Au  -f-  3S.  247.5. 


Platinum.  281 


PLATINUM.     Symb.  PI.     Equiv.  98.8.     Sp.  gr.  21.25. 

Platinum  is  a  very  rare  metal.  It  occurs  native  in  Brazil, 
Peru,  and  other  countries  of  South  America,  in  rounded  or 
flattened  grains,  mingled  with  other  metals.  It  is  found  in 
larger  quantities  in  the  Ural  Mountains. 

Properties.  Platinum  is  the  most  dense  of  the  metals,  of 
a  white  color,  resembling  silver.  It  is  malleable,  and  so  duc- 
tile that  it  may  be  drawn  into  wire  not  exceeding  -j-g2^  of 
an  inch  in  diameter.  It  is  soft,  and  easily  welded,  conduct- 
ing caloric  with  less  facility  than  many  other  metals.  It  is 
not  attacked  by  any  of  the  pure  acids.  Its  solvent  is  chlo- 
rine, or  nitrohydrochloric  acid.  It  is  fused  before  the  com- 
pound blowpipe,  and  by  voltaic  electricity. 

Spongy  Platinum*  has  the  remarkable  property  of  causing 
oxygen  and  hydrogen  gases  to  combine.  Platinum  foil  will 
produce  similar  effects.  This  is  due  to  the  attraction  of  the 
gases  for  the  platinum,  and  the  repulsive  power  of  the  gases 
themselves.  They  are  thus  so  condensed  upon  the  surface 
as  to  bring  the  particles  of  the  gases  within  the  sphere  of 
each  other's  attraction. 

Erp.  Let  a  jot  of  hydrogen  and  oxygen  upon  a  piece  of  spongy 
platinum  ;  the  gas  will  soon  be  inflamed. 

Protoxide  of  Platinum  (PI  -|-  O.  lOG.d)  is  prepared  by  digesting  pro- 
tochloride  of  platinum  in  a  solution  of  pure  potassa. 

Biiwxide  of  Platinum  (PI  -f2O  or  P1O2.  114.8)  is  prepared  with  diffi- 
culty. According  to  Berzelins,  it  should  be  prepared  by  exactly  de- 
composing sulphate  of  binoxide  of  platinum  with  nitrate  of  baryta,  and 
adding  pure  soda  to  the  filtered  solution,  so  as  to  precipitate  about 
half  of  the  oxide,  which  falls  as  a  bulky  hydrate,  of  a  yellowish-brown 
color. 

Sesquioxide  of  Platinum.  2P1-J-3O.  221.6.  This  oxide,  of  a  gray 
color,  is  prepared  by  heating  fulminating  platinum  with  nitrous  acid. 

Protocfdoride  of  Platinum  (P1+C1.  134.22)  is  formed  when  the 
bichloride  is  heated  to  450°;  half  of  its  chloride  is  expelled,  and  the 
protochloride,  of  a  greenish-gray  color,  remains. 

Bichloride  of  Platinum.  PI  -f  2C1.  169.64.  This  chloride  is  obtained 
by  evaporating  the  solution  of  platinum  in  nitrohydrochloric  acid  to 
dryness,  at  a  very  gentle  heat,  when  it  remains  as  a  red  hydrate, 
which  becomes  brown  when  its  water  is  expelled.  —  (See  Turner, 
page  408.) 

*  The  sponge  is  prepared  by  adding  ammonia  to  a  solution  of  the 
chloride,  and  heating  the  precipitate  to  drive  off  the  ammonia  and 
chlorine. 

24* 


282         %  Metals.  —  Platinum. 

Protiodide  uf  Platinum.   PI  -j-  I.  225.1. 

Biniodidt  of  Platinum  (PI  -f-  21.  351.4)  is  prepared  by  the  action  of 
iodide  of  potassium  on  a  rather  dilute  solution  of  bichloride  of  platinum. 
It  is  a  black  powder,  tasteless,  inodorous,  and  insoluble  in  water. 

Protosnlphuret  of  Platinum  (PI  +  S.  114.9)  is  prepared  by  heating 
the  ammoniacal  chloride  with  half  its  weight  of  sulphur,  until  all  the 
sal-ammoniac  and  excess  of  sulphur  are  expelled. 

Bisulphurct  of  Platinum  (Pl-f-2S.  131)  is  prepared  by  dropping  a 
solution  of  bichloride  of  platinum  into  a  solution  of  sulpnuret  of  po- 
tassium. 

fulminating  Platinum  may  be  prepared  by  the  action  of 
ammonia  in  excess  on  the  sulphate  of  protoxide  of  platinum. 
It  explodes  at  420°  with  a  very  loud  report,  but  does  not 
explode  by  percussion. 

Palladium,  Rhodium,  Osmium,  and  Iridium,  are  found 
associated  with  platinum,  but  exist  in  small  quantities. 

Palladium  (Pd.  53.3.  Sp.  gr.  11.5)  was  discovered  by 
Wollaston,  and  resembles  platinum  in  color  and  lustre. 

Rhodium  (R.  52.2.  Sp.  gr.  11)  was  also  discovered  by 
Wollaston.  It  is,  when  fused,  of  a  white  color,  hard,  and 
extremely  brittle.  It  attracts  oxygen  at  a  red  heat,  and  a 
mixture  of  peroxide  and  protoxide  of  rhodium  is  formed, 
not  acted  upon  by  any  of  the  acids,  unless. alloyed  with  other 
metals. 

Osmium  (Os.  99.7.  Sp.  gr.  7  to  10)  was  discovered  by 
Tennant,  in  1803.  It  is  a  black  powder,  which  acquires 
metallic  lustre  by  friction.  When  heated  in  the  open  air,  it 
takes  fire,  and  is  readily  oxidized  and  dissolved  by  fuming 
nitric  acid. 

Osmic  Acid  (Os-j-4O.  137.7)  is  formed  by  the  oxidation 
of  osmium  by  acids,  by  combustion,  or  by  fusion  with  nitre 
or  alkalies.  Its  vapor  is  very  acrid,  exciting  cough,  irritating 
the  eyes,  and  producing  a  copious  flow  of  saliva.* 

Iridium  (Ir.  98.8.  Sp.  gr.  15.3629)  was  discovered  by 
Tennant,  in  1803,  and  about  the  same  time  by  Descotils,  of 
France.  It  is  the  most  infusible  of  all  metals,  very  brittle, 
and  when  polished  resembles  platinum.t 


*  For  other  compounds  of  osmium,  see  Turner,  5th  ed.  p.  412. 
t  Iridium  forms  with  oxygen  four  < 
chlorides.     (See  Turner,  5th  ed.  p.  414. 


t  Iridium  forms  with  oxygen  four  oxides,  and  with  chlorine  four 
"thed. 


Salts.  283 

Latanium  (La)  is  a  metal  recently  discovered  by  Mosander. 
It  is  prepared  by  calcining  the  nitrate  of  cerium,  mixed  with 
nitrate  of  latanium. 


CHAPTER     III. 
CLASS  III.     SALTS,  OR  SECONDARY  COMPOUNDS. 

Salts  comprise  a  very  extensive  class  of  compounds,  in 
which  acids  combine  with  oxides,  or  with  other  compounds 
having  similar  properties.  The  oxide  which  combines  with 
the  acid,  is  termed  a  base,  or  salifiable  base. 

The  substances  hitherto  described  are  either  simple  bodies, 
or,  with  a  few  exceptions,  compounds  of  two  simple  elements, 
and  are  hence  called  binary  compounds. 

Salts,  on  the  other  hand,  are  composed  of  three  or  more 
simple  bodies,  and  are  hence  termed  secondary  compounds. 
As  salts,  under  favorable  circumstances,  readily  assume  regu- 
lar crystalline  forms,  it  seems  proper,  before  proceeding  to 
describe  them,  to  present  the  subject  of  crystallization  in 
general. 

SECTION  1.     CRYSTALLIZATION. 

Most  bodies,  under  favorable  circumstances,  may  be  made 
to  assume  the  form  of  a  regular  geometrical  solid.  The 
process  by  which  such  a  body  is  produced  is  called  crystal- 
lization ;  the  solid  is  termed  a  crystal;  and  the  science,  the 
object  of  which  is  to  study  the  form  of  crystals,  is  crystal- 
ography.  The  condition,  by  which  this  process  is  peculiarly 
favored,  is  the  slow  and  gradual  change  of  a  fluid  into  a 
solid,  the  arrangement  of  the  particles  being  at  the  same  time 
undisturbed  by  motion.  This  is  exemplified  during  the  slow 
cooling  of  a  fused  mass  of  sulphur  or  bismuth,  or  the  spon- 


284 


Salts.  —  Crystalography. 


taneous  evaporation  of  a  saline  solution.    The  numerous  crys- 
tals found  in  the  mineral  kingdom  are  due  to  the  same  cause. 

The  surfaces  which  limit  the  figure  of  crystals  are  called 
planes  or  faces.  The  lines  formed  by  the  junction  of  two 
planes  are  called  edges,  and  the  angle  formed  by  two  such 
edges  is  a. plane  angle;  a  solid  angle  is  the  point  formed  by 
the  meeting  of  at  least  three  planes.  —  T. 

The  forms  of  crystals  are  exceedingly  diversified;  they 
may  be  divided  into  primary  and  secondary  forms. 

The  primary  forms  are  fifteen  in  number,  and  may  be 
distributed  as  follows  :  —  1.  Prisms ;  2.  Octohedrons;  3.  Do- 
decahedrons. 

I.  The  prisms  have  either  a  six-sided  base,  or  nfo 
base. 


(1.)  Right  Prisms. 

The  bases  are  either  right  *  or  oblique, 
and  the  prisms  are  named  according  to 
their  bases. 

1.  The  Hexahedron,   or  Cube,  (Fig. 
89,)  is  a  figure  bounded  by  six  square 
faces,  and  all  the  angles  of  its  edges  are 
equal  to  90  degrees. 

2.  The  Right  Square  Prism  (Fig.  90) 
differs  from  the  cube  in  having  its  four  lat- 
eral planes  c,  c,  c,  c,  rectangles,  and  the  ter- 
minal planes  a  a  squares. 

3.  The  Right  Rectangular  Prism  (Fig. 
90)  differs  from  the  former  in  having  the 
terminal  planes  a,  a,  rectangular  instead  of 
square. 

4.  The  Right  Rhombic 
Prism    (Fig.  91)    differs 
from   the   two    preceding 
only  in  its  terminal  planes 
a,  bt  being  rhombs. 

5.  The   Right   Rhom- 
boidal    Prism    (Fig.  92) 


Fig.  89. 


Fig.  90. 


Fig.  91, 


Fig.  92. 


*  The  term  right  denotes  that  the  lateral  and  terminal  planes  are 
inclined  to  each  other  at  a  right  angle.    It  is  used  in  opposition  to 


Crystalography . 


285 


96. 


differs  from  the  preceding  form  in  the   terminal  planes  cc 
being  rhomboids. 

6.  The   Regular   Hexagonal    Prism 
(Fig.  93)   is  bounded  by  six  perpendicu- 
lar or  lateral  planes,  and  two  horizontal 
or  terminal  planes,  a,  t,  which  are  at  right 
angles  to  them. 

(-2.)    Oblique  Prisms. 

7.  The     Rhombohcdron        -,.      Oj<  -,. 
(Fig.    94)    is    bounded    by          'S' °4'  F'S> 

six   rhombic   faces,    of  the 
same  size  and  form. 

'  8.  The  Oblique  Rhombic 
Prisms  (Fig.  95)  have  the 
terminal  planes  «,«,  rhombs, 
with  the  lateral  planes  forming  oblique  angles  with  them. 

9.  Oblique  Rectangular  Prism  differs  from  the  preceding 
in  having  the  terminal  planes  rectangles. 

10.  Oblique   Rhomboidal    Prism    (Fig. 
96)  differs  from  the  two  preceding  forms 
in  the   terminal  planes  a,  a,  being   rhom- 
boids. 

11.  The  Octahedrons  are  also  named  from 
their  bases.     The  base  of  the  octohedron 
is  a  section  passing  through  four  angles. 

11.  Regular  Octohe- 
dron   (Fig.  97)    has    a  Fig.  97. 
square  base,  a  a  a  a,  and 

is  contained  under  eight 
equilateral  triangles  — 
hence  all  its  plane  an- 
gles are  equal  to  60  de- 
grees.  This  figure  is  a 
regular  solid  of  geom- 
etry. 

12.  Square    Octohe- 
dron   (Fig.    98)    has  a 

square  base,  aaaa,  and  is  bounded  by  eight  faces,  which  are 
isosceles  triangles.  *  The  base  is  always  a  square,  the  only 
part  of  the  figure  which  is  constant. 

oblique,  which  signifies  that  the  sides  are  not  perpendicular,  but  form 
an  oblique  angle  with  the  terminal  planes.  —  T. 


286 


Crystalography. 


13.  Rectangular    Octahedron    (Fig. 
99)  has  a  rectangular  base,  aaaa,  and 
is  bounded  by  eight  isosceles  triangles, 
four  of  which  are  different  from  the  other 
four. 

14.  Rhombic  Octohcdron  (Fig.   100) 
has  a  rhombic  base,  aaaa,  and  is  con- 
tained under  eight  similar  scalene  trian- 
gles, but  all  its  dimensions  are  variable. 


III.    Dodecaliedrons. 

15.  There  is  but  one  pri- 
mary dodecahedron,  called 
the  rhombic  dodecahedron, 
(Fig.  J01,)  and  is  limited 
by  twelve  similar  rhombic 
faces;  the  faces  incline  to 
each  other  at  an  angle  of 
120  degrees  • 


.  99. 


Fig.  101. 


Secondary  Forms. 

The  secondary  forms  of  crystals  are,  very  numerous, 
amounting  to  millions.  The  forms  of  a  single  mineral  calca- 
reous spar  have  been  found  to  be  nearly  a  thousand ;  but  each 
of  the  secondary  forms  may  be  reduced  to  one  or  more  of 
the  primary,  by  a  process  called  cleavage.  This  proc<  —  b 
usually  performed  with  a  sharp  instrument,  by  removing  thin 
laminae  from  the  faces,  edges,  or  angles  of  the  crystal.  The 
surfaces  exposed  by  splitting  or  cleaving  a  crystal,  are 
termed  the  faces  of  cleavage,  and  the  direction  in  which  it 
may  be  cleaved  is  called  the  direction  of  cleavage.  Some 
crystals  are  cleavable  in  one  direction,  and  some  in  two,  three, 
four,  or  more  directions. 

Those  which  cleave  in  more  than  two  directions  may,  by 
the  removal  of  layers  parallel  to  the  planes  in  their  cleavage, 


*  The  instrument  used  for  measuring  the  angles,  at  which  the  planes 
of  crystals  meet,  or  incline  to  each  other,  are  called  goniometers.  —  See 
Dana's  Mineralogy,  p.  32,  New  Haven.  1837. 


Oxy-Salts.  287 

be  made  to  assume  regular  primary  forms,  whatever  be  their 
figure  previous  to  cleavage. 

It  was  formerly  supposed  that  each  substance  always  had 
the  same  primary  form  ;  but  the  discovery  was  made  by 
Mitscherlich,  in  1819,  that  identity  of  composition  did  not 
always  indicate  identity  of  crystalline  form. 

To  this  new  branch  of  science  the  term  isomorphism 
(from  /aoc,  equal,  and  /JO^T),  form)  is  applied.* 

The  phenomena  of  crystallization  are  ascribed  to  cohesive 
attraction,  or,  more  properly,  to  crystalogenic  attraction. 

The  crystallization  of  salts  is  most  readily  effected  by  dis- 
solving them  in  water,  and  evaporating  the  solution. 

Exp.  Introduce  into  a  large  matrass  a  pound  and  a  half  of  Glauber  a 
salts,  (sulphate  of  soda,)  with  a  pound  of  water,  and  boil  the  mixture 
until  all  the  salt  is  dissolved ;  cork  it  tight,  as  the  heat  is  removed,  and 
let  it  cool.  On  taking  out  the  stopper,  the  salt  will  suddenly  crystal- 
lize, and  the  whole  will  become  nearly  solid. 

The  water  enters  into  the  crystal  in  definite  proportions, 
and  is  called  the  water  of  crystallization.  The  quantity  of 
combined  water  is  very  variable  in  different  crystals;  such 
salts,  when  heated,  dissolve,  if  soluble,  in  their  own  water 
of  crystallization,  undergoing  what  is  termed  watery  fusion : 
some  salts,  when  exposed  to  the  air,  lose  their  water  of  crys- 
tallization, and  crumble  down  into  a  fine  powder  ;  this  is 
termed  efflorescence:  others  absorb  water  from  the  atmos- 
phere, and  are  said  to  deliquesce. 

Some  salts  enclose  mechanically  within  their  texture  parti- 
cles of  water,  by  the  expansion  of  which,  when  heated,  they 
burst  with  a  crackling  noise ;  this  is  called  decrepitation. 

The  salts  are  divided  into  four  orders  :  — 


SECTION  2. 
ORDER  I.  — GXY-SALTS. 

This  order  includes  no  compound  the  acid  or  base  of 
which  does  not  contain  oxygen.     All  the  powerful  alkaline 

*   *  See  Turner,  5th  ed.  p.  429. 


288  Salts.  —  Sulphates. 

bases,  except  ammonia,  are  protoxides  of  an  electro-positive 
metal.  If  M  represent  an  equivalent  of  any  metal,  M-|-O 
or  MO  is  the  strongest  alkaline  base,  and  generally  the  only 
one  which  the  metal  is  capable  of  forming;  a  single  equiv. 
of  acid  neutralizes  MO,  forming  a  neutral  salt.  Thus,  if 
an  equiv.  of  sulphuric  and  nitric  acids  be  represented  by 
SO3  and  NO5,  all  the  neutral  sulphates  and  nitrates  of  the 
protoxide  will  be  indicated  by  MO  -fr  SO3  and  MO  +  NO5 ; 
hence  it  may  be  inferred,  that,  in  each  family  of  salts,  there 
is  a  constant  ratio  in  the  oxygen  of  the  base  and  that  of 
the  acid;  that  for  sulphates  is  as  1  to  3,  and  the  nitrite- 
as  1  to  5.  If  the  base  be  a  binoxide,  the  same  relation 
is  preserved. 

Saks  sometimes  combine  with  each  other,  forming  double 
salts ;  these  are  composed  of  two  acids  and  one  base,  of  two 
bases  and  one  acid,  or  of  two  different  acids  and  two  differ- 
ent bases ;  these  were  formerly  called  triple  salt*. 

Those  salts  which  are  formed  by  the  same  acid,  combined 
with  different  bases,  have  many  properties  in  common,  and 
hence  they  are  classed  in  the  same  family. 


^.  SULPHATES. 

Many  of  the  sulphates  occur  native;  of  which,  those  of 
lime  and  baryta  are  the  most  abundant.  They  may  all  be 
formed  by  the  action  of  sulphuric  acid  on  the  metals,  their 
oxides,  their  carbonates,  or  by  double  decomposition.  They 
vary  in  solubility  in  water,  and  are  all  decomposed  at  a  white 
heat,  and  by  carbonaceous  matter  with  the  aid  of  heat. 

Sulphuric  Acid,  which  is  the  acid  of  all  the  sulphates,  is 
readily  detected  by  the  chloride  of  barium  —  the  acid  having 
a  stronger  affinity  for  baryta  than  for  any  other  alkaline 
base. 

The  sulphates  are  a  very  numerous  family  of  salts.  The 
following  are  the  most  important :  — 

Sulphate  of  Potassa,  (KO  -f-  SO3.  87.25,)  yotassa  sulphas, 


Sulphates.  —  Potassa.  —  Soda.  289 

was  formerly  called  sal  de  duobus.     It  may  be  prepared  by 
neutralizing  carbonate  of  potassa  with  sulphuric  acid. 

Properties.  Taste  saline  and  bitter.  Its  crystals  belong 
to  the  right  prismatic  system,  and  contain  no  water;  soluble 
in  16  times  their  weight  of  water  at  60°,  and  in  5  of  boiling 
water. 

Bisulphate  of  Potassa.  KO-f  2SO3.  127.35;  with  1 
equiv.  of  water,  136.35.  This  salt  is  prepared  by  heating 
the  sulphate,  with  half  its  weight  of  sulphuric  acid,  in  a 
platinum  crucible. 

Properties.  It  has  a  sour  taste,  and  reddens  litmus 
paper;*  is  more  soluble  than  the  sulphates,  and  its  crystals 
belong  to  the  same  order.  It  is  used  for  cleaning  coin,  and 
other  works  in  metal. 

Sulphate  of  Soda  (NaO  +  SO3.  71.4;  in  crystals,  with  10 
equiv.  of  water,  161.4)  is  well  known  as  Glauber's  salts. 
It  is  found  in  the  earth,  and  in  the  water  of  many  springs. 
It  is  easily  formed  by  saturating  SO3  with  carbonate  of 
soda. 

Properties.  Taste  bitter,  cooling,  and  saline.  Its  crys- 
tals belong  to  the  right  prismatic  system;  effloresces  on 
exposure  to  the  air,  and  undergoes  watery  fusion  when 
heated.  12. parts  of  the  salt  require  100  of  water  at  32° 
to  dissolve  them.  Used  in  pharmacy,  and  in  the  manufac- 
ture of  glass. 

Bisulpkate  of  Soda.  NaO-f-SSO3.  111.5;  with  4  equiv.  of  water, 
147.5. 

Suipltate  of  Litha  (LO-f-SO3.  58.1;  in  crystals,  with  1  equiv.  of 
water,  67.1)  has  a  saline  taste,  very  soluble  and  fusible,  and  crystal- 
lizes in  flat  prisms. 

Sulphate  of  Ammonia  (H3N  -f-  SO3.  57.25 ;  in  crystals,  with  1  equiv. 
of  water,  67.1)  sometimes  occurs  native  in  volcanoes,  and  near  cer- 
tain small  lakes  in  Tuscany.  It  may  be  prepared  by  neutralizing 
sulphuric  acid  with  carbonate  of  ammonia.  It  is  contained  in  soot 
from  coal. 

Properties.  It  crystallizes  in  long,  flattened,  six-sided 
prisms,  soluble  in  2  parts  of  water  at  60°,  and  in  an  equal 
weight  of  boiling  water;  effloresces  in  warm,  dry  air,  losing 

*  Unglazed  paper,  moistened  in  an  infusion  of  litmus,  and  dried. 


290  Salts.  —  Sulph  ates. 

1  eqniv.  of  water;  yields  its  water  of  crystallization  by 
heat,  fuses,  and  is  decomposed,  yielding  nitrogen,  water, 
and  sulphate  of  ammonia. 

Uses.  It  is  the  source  of  the  hydrochlorate  of  ammonia,  which  is 
obtained  by  a  mixture  of  common  salt  and  sulphate  of  ammonia  by 
sublimation. 

Sulphate  of  Baryta  (BaO  +  SO3.  116.8.  Sp.  gr.  4.4) 
occurs  native  in  great  abundance,  and  is  known  by  the 
name  of  heavy-spar. 

Properties.  Insoluble  in  water,  and  is  precipitated  by 
adding  sulphuric  acid  to  any  soluble  salt  of  baryta.  So 
delicate  is  baryta  as  .a  test  of  SO3,  that  1  part  of  sulphate 
of  soda  in  400,000  .of  water  is  detected  by  it.  It  fuses  at 
a  high  temperature  into  an  opaque,  white  enamel. 

Uses.  It  is  employed  in  the  manufacture  of  jasper  irare,  and  for  a 
paint  under  the  name  of  permanent  white.*  (See  Baryta,  page  227.) 

Sulphate  of  Strontia  (SrO  +  SO3.  91.9)  occurs  native  in 
beautiful  crystals  in  Sicily,  and  also  on  Strontian  Island, 
Lake  Erie. 

Properties.  It  has  a  blue  tint,  and  is  called  celestine; 
sometimes  it  is  colorless  and  transparent ;  nearly  insoluble, 
requiring  4000  parts  of  cold,  and  3840  of  hot  water  to 
dissolve  it.  Heated  with  charcoal,  its  acid  is  decomposed, 
and  sulphuret  of  strontium  is  formed. 

Sulphate  of  Lime  (CaO  +  SO3.  68.6;  with  2  equiv.  of 
water,  86.6)  occurs  in  nature  in  large  quantities.  Every 
'variety  of  gypsum  is  the  sulphate  combined  with  2  equiv. 
of  water;  such  as  plaster  of  Paris,  selenite, —  which  is  a 
crystallized  variety,  —  alabaster,  a  white,  compact  varie- 
ty, used  in  statuary,  —  and  anhydrite t  which  contains  no 
water.  The  salt  may  be  formed  by  mixing,  in  solution,  a 
saltrof  lime  with  any  soluble  sulphate. 

Properties.  Crystals  of  anhydrite  belong  to  the  right,  and 
of  gypsum  to  the  oblique  prismatic  systems.  It  is  nearly 
tasteless,  soluble  in  500  parts  of  cold,  and  450  of  boiling 

*  It  is  the  best  paint  for  marking  phials  and  jars  in  the  laboratory. 
It  may  be  prepared  by  mixing  the  powder  with  oil  and  lampblack. 


Sulphates.      ^  291 

water ;  hence  it  is  generally  found  in  spring  and  river  w  ater, 
and  especially  in  those  waters  called  hard.  Baryta  will  de- 
tect the  sulphuric  acid,  and  oxalic  acid  the  lime.  Heated  to 
212°  in  vacua,  it  parts  with  1  equiv.  of  water,  and  at  300° 
the  whole  ;  in  this  state  it  is  used  as  a  cement.  By  mixing 
it  with  a  certain  portion  of  water,  it  hardens  rapidly,  and  be- 
comes dry  and  so^id  ;  on  this  account  it  is  much  used  for 
taking  impressions,  for  stereotype  plates,  and  for  casts,  busts, 
and  a  great  variety  of  purposes  in  the  arts.  It  is  used  in 
agriculture  as  a  mineral  manure,  and  is  highly  useful  to 
most  soils. 

Sulphate  of  Magnesia  (MgO-\-SO*HO.  69.8;  in  crystals, 
with  (5  equiv.  of  water,  =  123.8)  was  procured  from  the 
springs  of  Epsom,  England,  and  hence  called  Epsom  salt. 
It  is  found  native,  and  constitutes  the  bitter  salt  and  hair 
salt  of  mineralogists.  Sometimes  it  is  found  incrusting  the 
damp  walls  of  cellars  and  new  buildings.  Many  saline 
springs  contain  it. 

Process.  But  it  is  generally  obtained  from  sea-water,  and 
exists  in  the  bittern  which  is  left  after  the  crystallization  of 
common  salt.  It  is  obtained  by  decomposing  the  hydro- 
chlorate  of  magnesia  contained  in  it  with  SO3.  It  may  also 
be  formed  from  the  carbonate  by  adding  sulphuric  acid. 

Properties.  It  has  a  saline,  bitter,  and  nauseous  taste. 
Its  crystals  are  small,  quadrangular  prisms,*  slightly  efflores- 
cent in  dry  air,  soluble  in  an  equal  weight  of  water  at  60°, 
and  £  of  their  weight  of  boiling  water.  They  undergo  watery 
fusion  when  heated,  and  are  partially  decomposed  at  a  white 
heat. 

Sulphate  of  Alumina.  2AlO3-f-SO3.  91.5  j  in  crystals,  with  9  equiv. 
of  water,  172.5 

Tersulphate  of  Alumina.  2A1O1  -f  3SO3.  171.7;  in  crystals,  with  18 
equiv.  of  water,  333.7. 

The  Hi/drated  Disulphate  is  calted  Mumlnite. 

Sulphate  of  Protoxide  of  Manganese.     MnO  -{-  SO3IIO.  84.8. 

Sulphate  of  Protoxide  of  Iron.  FeO  +  SO3HO.  85.1 ;  in 
crystals,  with  5  equiv.  of  water,  eq.  130.1.  This  is  known 

*  The  larger  crystals  are  generally  right  rhombic  prisms. 


292  Salts.  —  Sulphates. 

by  the  name  of  green  vitriol,  or  copperas.  It  is  prepared  on 
a  large  scale  for  the  arts,  by  exposing  the  native  protosulphu- 
ret  of  iron  to  air  and  moisture ;  the  iron  is  converted  into 
an  oxide,  and  the  sulphur  into  SO3 ;  they  then  combine  and 
form  the  sulphate.  It  may  also  be  formed  by  the  action  of 
SO3  on  the  iron. 

Properties.  Its  taste  is  strongly  styptic  and  inky.  When 
pure,  it  does  not  redden  the  vegetable  blue  colors.  Its  crys- 
tals have  a  blue  tint,  and  belong  to  the  oblique  prismatic 
system  ;  soluble  in  2  parts  of  cold,  and  in  £  its  weight  of 
boiling  water.  It  is  used  in  the  manufacture  of  fuming  sul- 
phuric acid  and  in  dyeing. 

Tersulphate  of  the.  Seyuioxide.  Fe^3  +  3SQ3.  200.3. 

Disulphate  of  the  Sequioxidc.  2Fe2O3  +  SO*.  200.1. 

Sulphate  of  the  Protoxide  of  Zinc,  (ZnO  +  SC^HO.  89.4  ; 
with  6  equiv.  of  water  =.  143.4,)  commonly  called  white  vitriol, 
is  formed  by  the  action  of  dilute  sulphuric  acid  on  zinc.  It 
is  prepared  in  the  arts  by  roasting  the  native  sulphuret  of 
zinc. 

Properties.  It  crystallizes,  by  spontaneous  evaporation,  in 
transparent,  flattened,  four-sided  prisms,  referable  to  a  rii/ht 
rhombic  prism,  and  isomorphous  with  Epsom  salt.  Taste 
strongly  styptic,  and,  although  a  neutral  salt,  reddens  vegeta- 
ble blue  colors;  soluble  in  2|  parts  of  cold,  and  a  less  quan- 
tity of  boiling  water. 

Use.  A  powerful  emetic,  and  poisonous  if  given  in  large 
doses. 

Sulphate  of  Protoxide  of  Nickel  (NiO  +  SO3HO.  86.6) 
crystallizes  from  its  solution  in  pure  water,  in  right  rhombic 
prisms,  and,  like  most  of  the  salts  of  nickel,  is  of  a  green 
color. 

Sulphate  of  Protoxide  of  Cobalt  (CO  +  SO3HO.  86.6)  is 
formed  by  digesting  dilute  SO3  with  oxide  of  cobalt.  On 
evaporation,  it  appears  in  the  form  of  red  crystals. 

Tersulphate  of  the-  Sequioxide  of  Chromium.  Cr2O3  4-  3 
SO3.  200.3. 


Sulphates.  293 

Sulphates  of  the  Oxide  of  Copper. 

The  Disulphate  (2CuO  -f  SO3.  1 19.3)  has  not  been  ob- 
tained in  a  separate  state. 

The  Sulphate,  or  Blue  Vitriol*  (CuO  +  SO3HO.  88.7 ;  in 
crystals,  with  4  equiv.  of  water,  124.7)  is  formed  by  roasting 
the  native  sulphuret,  or  by  dissolving  the  protoxide  in  dilute 
sulphuric  acid,  and  crystallizing  by  evaporation. 

Properties.  The  crystals  are  of  a  blue  color,  and  yield  4 
cquiv.  of  writer  at  212°,  and  the  whole  at  430°  Fahr.,  when 
it  becomes  a  white  powder. 

When  ammonia  is  dropped  into  a  solution  of  the  sulphate, 
it  forms  a  dark  blue  solution,  from  which,  when  concentrated, 
crystals  are  deposited  by  the  addition  of  alcohol.  This  is  the 
ammoniarit  of  copper  of  the  U.  S.  Phar. 

Sulphate  of  the  Oxides  of  Mercury. 

The  Sulphate  of  Protoxide  (HgO+  SO3.  250.1)  is  formed 
when  '2  p  irts  of  mercury  are  heated  with  3  of  strong  sul- 
phuric acid,  so  as  to  produce  effervescence.  If  a  strong  heat 
is  employed,  the 

Bisulphate  (HgO2-f2SO2.  298.2)  results,  both  being  an- 
hydrous. When  this  bisulphate  (the  salt  employed  for 
making  corrosive  sublimate)  is  thrown  into  hot  water,  a  yel- 
»  >\v  salt,  the 

Sitbtulphate,  (4HgO2  +  3SO3.  992.3,)  called  turpeth  min- 
eral, is  generated. 

Sulphate  of  Oxide  of  Silver  (AgO  +  SO3.  156.1)  is  depos- 
ited when  sulphate  of  soda  is  mixed  with  nitrate  of  silver, 
and  also  by  boiling  silver  with  its  weight  of  sulphuric  acid. 

Properties.  It  is  white,  and  easily  fused ;  soluble  in  80 
times  its  weight  of  hot  water,  and  deposits  small,  needle- 
shaped  crystals  on  cooling.  It  forms  with  ammonia  a  double 
salt,  consisting  of  1  equiv.  of  oxide  of  silver,  1  of  acid, 
and  2  of  ammonia.  It  crystallizes  in  rectangular  prisms, 
isomorphous  with  the  double  chromate  and  seleniate  of  oxide 
of  silver  and  ammonia. 

*  Great  use  is  now  made  of  this  substance  for  exciting  electricity  in 
galvanic  batteries. 

25* 


294  Salts.— Sulphates. 

Nitrosulphuric  Acid,  consisting  of  1  part  of  nitric  dis- 
solved in  10  of  sulphuric  acid,  dissolves  silver,  but  scarcely 
acts  upon  copper,  lead,  or  iron,  unless  diluted  with  water ; 
hence  its  use  in  separating  silver  from  old  plated  articles. 

Double  Sulphates. 

Sulphate  of  Soda  and  Liw«  (NaOSO3  +  CaOSO3.  140)  is  the  Glnuber- 
ite  of  mineralogists,  and  occurs  in  the  salt-mines  of  New  Castle. 

Sulphate  of  Putassa  and  Magnesia  (KOSCH  +  MgOSO3)  is  formed 
by  mixing  solutions  of  the  two  salts. 

Sulphate  of  Potassa  and  Alumina.  KOSO3  + Al^K)3.  3SO3. 
258.95,  do.  with  24  equiv.  of  water  =  474.95.  This  salt, 
the  common  alum,  is  prepared  by  roasting  and  lixiviating  cer- 
tain clays,  containing  iron  pyrites,  and  adding  to  the  lyes  a 
quantity  of  sulphate  of-potassa.  It  is  obtained  in  Italy  from 
alum-stone.  Alum  is  also  found  in  volcanic  countries,  pro- 
duced by  the  action  of  sulphurous  vapors  on  rocks  com  urnm: 
feldspar. 

Properties.  It  has  a  sweetish,  astringent  taste ;  is  soluble 
in  5  parts  of  water  at  60°,  and  crystallizes  in  octohedr<»:i- 
Ignited  with  charcoal,  it  forms  Homberg's  Pyrophorus. 

Exp.  Take  3  parts  of  lampblack.  4  of  calcined  alum,  and  8  of  jx-arl- 
afches;  mix  them  thoroughly,  and  heat  them  inan  iron  tube  to  a  bright 


cherry-red,  for  one  hour;  on  removal  from  the  fire,  the  tube  must  be 

carefully 

breathed  upon,  ignites  with  slight  explosions.     The  essential  part  is 


stopped.     This   substance,   when   exposed   to   the   air  and 
upon,  ignites  with  slight  explosions.     Tin 
probably  sulphurct  of  potassium^  in  minute  divisions. 

Use.  Alum  is  of  great  use  in  the  arts,  especially  in  dye- 
ing and  calico-printing,  because  of  its  attraction  for  coloring 
matter. 

Ammonia  Alum  has  the  same  form,  appearance,  and  taste. 

Soda  Alum  is  also  similar,  except  that  it  contains  26  equiv. 
of  water. 

Iron  Alum  is  formed  by  mixing  sulphate  of  potassa  with 
tersulphate  of  sesquioxide  of  iron;  it  resembles  common 
alum  in  form,  color,  taste,  and  composition. 

Chrome  Alums.  The  tersulphate  of  sesquioxide  of  chro- 
mium forms  double  salts,  with  the  sulphate  of  potassa  and 
ammonia,  very  similar  to  the  preceding. 


Sulphites  —  Nitrates.  295 

Manganese  Alum  is  formed  by  mixing  a  solution  of  ter- 
sulphate  of  sesquioxide  of  manganese  with  sulphate  of  po- 
tassa.  These  salts  all  crystallize  in  the  octohedral  system, 
and  are  similar  in  composition,  one  oxide  being  substituted 
for  another,  to  form  the  different  varieties. 

2.  SULPHITES. 

The  salts  of  sulphurous  acid  have  not  hitherto  been  mi- 
nutely examined  ;  the  sulphites  of  potassa,  soda,  and  ammo- 
nia, are  made  by  neutralizing  those  alkalies  with  sulphurous 
acid,  and  are  soluble  in  water ;  but  most  sulphites  are  spar- 
ingly soluble,  if  at  all ;  they  are  decomposed  by  the  stronger 
acids.  —  (See  Turner,  5th  edit.  p.  443.) 

3.  NITRATES. 

The  nitrates  may  be  prepared  by  the  action  of  nitric  acid 
on  metals,  on  the  salifiable  bases,  or  on  carbonates,,  As 
nitric  acid  forms  soluble  salts  with  all  alkaline  bases,  the 
acids  of  the  nitrates  cannot  be  precipitated  by  any  re- 
agent. —  T. 

The  nitrates  are  all  decomposed  by  a  high  temperature, 
and  by  the  agency  of  heat  and  combustible  matter ;  hence 
they  are  much  employed  as  oxidizing  agents.  The  process 
of  oxidation  by  nitre,  is  called  deflagration,  which  is  gener- 
ally performed  by  mixing  the  inflammable  body  with  an  equal 
weight  of  the  nitrate,  and  projecting  the  mixture,  in  small 
portions,  into  a  red-hot  crucible.  All  the  neutral  nitrates  of 
the  fixed  alkalies  and  alkaline  earths,  together  with  most  of 
the  neutral  nitrates  of  the  common  metals,  are  composed  of 
1  equiv.  of  nitric  acid,  and  1  of  the  protoxide  ;  hence  the 
oxygen  of  the  base  is  to  that  of  the  acid,  as  1  to  5 ;  the 
general  formula  is  MO  -|-  NO5. 

Nitrate  of  Potassa  (KO-j-NO5.  101.3)  is  an  abundant 
natural  product;  it  is  obtained  from  the  East  Indies  by 
lixiviating  certain  soils  ;  in  Germany  and  in  France,  it  is  pro- 
duced in  what  are  termed  nitre-beds. 


206  Salts.  —  Nitrates. 

The  French  process  consists  in  lixiviating  old  plaster  rub- 
bish. Nitre  also  exudes  from  new  walls.  Some  caverns  in 
Kentucky  afford  nitrate  of  lime,  from  which  nitre  is  obtained 
by  adding  carbonate  of  potassa ;  it  is  also  found  under  old 
buildings,  and  is  commonly  called  nitre  and  saltpetre. 

Properties.  Colorless ;  has  a  saline  and  cooling  taste ; 
soluble  in  its  own  weight  of  boiling  water ;  crystallizes  in 
six-sided  prisms  without  any  water  of  crystallization ;  and 
fuses  at  <il6°. 

Fulminating  Powder  is  formed  of  3  parts  of  nitre,  2  of  dry 
subcnrbonate  of  potassa,  and  1  of  sulphur. 

Etp,  Heat  a  small  quantity  in  the  flame  of  a  spirit  lamp,  and  it  will 
explode  with  considerable  violence. 

Uses.  Used  in  chemistry  as  an  oxidizing  agent,  and  in 
the  formation  of  nitric  acid.  In  the  East  Indies,  it  is  em- 
ployed for  cooling  mixtures  ;  one  ounce  of  nitre  to  five  of 
water,  reduces  the  temperature  15°.  From  its  anti-septic 
properties,  it  is  employed  for  preserving  animal  substances. 

In  the  arts,  it  is  extensively  employed  in  the  manufacture 
of  gunpowder,  which  consists  of  nitre,  sulphur,  and  charcoal. 
In  agriculture,  it  is  used  as  a  manure. 

Nitrate  of  Soda,  (NaO  +  NO5.  85.45,)  called  by  the  old 
writers  cubic  nitre,  occurs  in  the  soils  of  India,  and  in 
Peru;  it  is  analogous,  in  chemical  properties,  to  the  pr« •<  •  - 
ding  ;  mixed  with  charcoal,  it  burns  more  slowly  than  nitre. 

Nitrate  of  Ammonia  (H3N  +  NO5.  71.3)  is  formed  by 
neutralizing  dilute  nitric  acid  by  carbonate  of  ammonia,  and 
evaporating  the  solution.  It  is  decomposed  by  heat,  and 
yields  the  exhilarating  gas  or  protoxide  of  nitrogen. 

Nitrate  of  Baryta  (BaO  +  NO5.  130.85)  is  easily  pre- 
pared by  digesting  the  native  carbonate  in  nitric  acid, 
diluted  with  8  or  10  parts  of  water ;  on  evaporation,  it 
crystallizes  in  transparent,  anhydrous  octohedrons ;  soluble 
in  12  parts  of  water  at  60°,  and  3  or  4  of  boiling  water. 
This  salt  is  used  as  a  re-agent,  for  preparing  pure  baryta, 
and  in  pyrotechny,  to  impart  a  green  color  to  flame.* 

*  The  green  fire  is  composed  of  13  parts  sulphur,  77  nitrate  of 
baryta,  5  chlorate  of  potassa,  2  of  arsenic,  and  3  of  charcoal. 


Nitrates.  297 

Nitrate  of  Strontia  (SrO-f-NO5.  105.95;  in  prisms, 
with  5  cquiv.  of  water,  =  150.95)  is  prepared  from  the  carbo- 
nate of  strontia,  in  the  same  manner  as  the  preceding,  and 
has  similar  properties ;  it  is  used  for  the  redjire  employed  at 
theatres.* 

Nitrate  of  Lime  (CaO  +  NO5.  82.65)  is  found  in  old 
plaster  and  mortar ;  very  soluble  and  deliquescent ;  crystal- 
lizes in  hydrated  prisms. 

The  Nitrate  of  Magnesia  (MgO  +  NO5.  74.85)  has  simi- 
lar properties. 

Nitrate  of  Protoxide  of  Copper  (CuO  +  NO5.  93.75)  is 
formed  by  the  action  of  nitric  acid  on  copper ;  its  crystals 
are  prisms  containing  7  equiv.  of  water,  of  a  deep  blue  color, 
soluble  in  water  and  alcohol,  and  deliquescent. 

Exp.  Spread  a  drachm  of  this  salt  on  a  piece  of  tin  foil,  moisten  it 
with  water,  fold  it,  and  lay  it  on  a  plate  ;  sufficient  heat  will  often  be 
evolved  to  ignite  the  metal. 

Nitrate  of  Protoxide  of  Lead  (PbO-j-NO5.  165.75)  may 
be  formed  by  digesting  litharge  in  dilute  nitric  acid ;  it  crys- 
tallizes in  anhydrous  octohedrons,  and  has  an  acid  re-action. 

Dlnitrate  of  Protoxide  of  Lead.  2PbO  +  NO5.  223.2  + 
54.15  =  277.35. 

Nitrate  of  Protoxide  of  Mercury  (AgO  +  NO5.  264.15; 
in  crystals,  with  2  equiv.  water,  =  282.15)  is  obtained  by 
digesting  mercury  in  nitric  acid,  diluted  with  3  or  4  parts  of 
water,  until  the  acid  is  saturated,  and  then  allowing  the  solu- 
tion to  evaporate  spontaneously  in  an  open  vessel. 

Nitrate  of  Peroxide  of  Mercury  (HgO2  +  NO5.  272.15) 
is  formed  by  heating  mercury  with  strong  nitric  acid  in 
excess. 

The  solution,  on  cooling,  deposits  transparent,  prismatic 
crystals;  when  this  salt  is  put  into  hot  water, "it  is  resolved 
into  a  soluble  salt,  whose  composition  is  unknown,  and  into 
a  yellow  dinitr ate  of  the  peroxide.  2HgO2  +  NO5.  490.15. 

Nitrate  of  Oxide  of  Silver  (AgO  +  NO5  170.15)  may  be 


*  Red  fire  consists  of  40  parts  of  nitrate  of  strontia,  ]  3  sulphur, 
5  chlorate  of  potassa,  and  4  sulphuret  of  antimony,  with  a  little  pow- 
dered charcoal. 


298  Salts.  — Nitrates. 

formed  by  dissolving  silver  in  nitric  acid,  diluted  with  ft 
parts  of  water ;  if  the  silver  contain  copper,  it  will  give  a 
greenish  hue  to  the  solution  ;  if  it  contain  gold,  it  will  appi^r 
in  the  form  of  a  black  powder.  The  solution  should  be  per- 
fectly clear  and  colorless.* 

Properties.  The  solution  by  evaporation  deposits  trans- 
parent, tabular  crystals ;  it  is  caustic,  and  tinges  animal  sub- 
stances of  a  deep  yellow,  which  becomes,  by  exposure  to 
light,  deep  purple  or  black,  and  is  indelible. 

Heated  in  a  silver  crucible  to  426°,  it  fuses,  and  when 
cast  into  small  cylinders,  forms  the  lunar  caustic  of  phar- 
macy. This,  when  pure,  is  white  and  transparent ;  but  the 
common  lunar  caustic  is  dark  and  opaque,  owing  to  the 
decomposition  of  the  nitrate,  by  raising  the  temperature  too 
high  in  its  preparation,  and  also  in  consequence  of  copper 
and  gold,  which  are  often  contained  in  it;  it  is  soluble  in  its 
own  weight  of  cold,  and  in  half  its  weight  of  boiling  water. 

It  is  decomposed  by  light,  leaving  a  black  stain  upon  th<» 
skin  or  on  paper,  (see  p.  68;)  hence  it  is  a  very  delicate  test 
of  animal  .matter,  also  of  chlorine  and  hydrochloric  acid, 
which  latter  causes  a  white  precipitate,  the  chloride  of  silver. 

It  is  also  decomposed  by  sulphur,  phosphorus,  charcoal, 
hydrogen,  and  several  of  the  metals.  J*; 

Exp.  Place  a  few  grains  of  this  salt,  with  a  little  sulphur,  and  also 
with  phosphorus,  upon  an  anvil ;  when  struck  sharply  with  a  hatiuin -r, 
the  former  will  detonate,  and  the  latter  explode  violently. 

Erp.  Dip  a  piece  of  silk  into  a  solution  of  this  salt,  and,  whil»-  inni.--t, 
pass  over  it  hydrogen  gas;  it  will  at  first  turn  black,  and  then  become 
iridescent,  from  the  reduction  of  the  metal. 

Erp.  Immerse  in  a  solution  of  this  salt  a  stick  of  phosphorus;  it  will 
soon  become  beautifully  inciusted  with  the  metal. 

Exp.  Immerse  a  slip  of  ivory  in  a  dilute  solution  of  the  salt,  till  th«> 
ivory  has  acquired  a  bright  yellow  stain  ;  remove  it  to  a  tumbler  of  dis- 
tilled water,  and  expose  it  to  the  direct  rays  of  the  sun  for  two  hours, 

*  One  of  the  best  solvents  of  silver  may  be  formed  by  dissolving  1 
part  of  nitre  in  10  by  weight  of  concentrated  sulphuric  acid.  When 
this  compound  is  heated  to  between  100°  and  200°  F.-ilir.,  it  will  dis- 
solve about  one  sixth  of  its  weight  of  silver  without  acting  in  the  least 
upon  any  copper,  gold,  lead,  or  iron,  with  which  the  silver  may  he 
combined  ;  hence  it  is  very  useful  to  detach  silver  from  old  plate.  To 
recover  the  silver  from  the  solution,  add  common  salt,  and  then  de- 
compose the  chloride  thus  formed  by  carbonate  of  soda. 


Nitrates  —  Chlorates.  299 

when  it  will  become  black,  but,  on  rubbing  it,  the  surface  will  become 
bright,  resembling  pure  silver. 

Nitrate  of  Silver  is  the  principal  ingredient  in  indelible 
ink,  and  in  those  compounds  which  are  used  for  changing 
the  color  of  the  hair. 

In  all  these  cases,  the  effect  depends  upon  the  reduction  of 
a  part  of  the  silver  to  the  metallic  state. 

4.     NITRITES. 
According  to  Turner,  very  little  is  known  of  these  salts. 

5.     CHLORATES. 

The  salts  of  chloric  acid  are  very  analogous  to  those  of 
nitric  acid.  They  are  all  soluble  in  water,  and  are  dis- 
tinguished by  the  action  of  strong  hydrochloric  and  sulphuric 
acids,  the  former  disengaging  chlorine,  and  protoxide  of  chlo- 
rine, and  the  latter  chlorous  acid. 

The  chlorates  are  mostly  composed  of  1  equiv.  of  protoxide 
and  1  of  acid  ;  hence  the  oxygen  of  the  base  is  to  that  of  the 
acid,  as  1  to  5,  or  Mo-)- CIO5. 

None  of  the  chlorates  are  found  native,  and  those  of  baryta 
and  potassa  are  the  only  ones  which  require  particular  notice. 

Chlorate  of  Potassa  (KO  -f  CIO5.  122.57)  may  be  formed 
by  transmitting  chlorine  gas  through  a  concentrated  solution 
of  pure  potassa,  until  the  alkali  is  completely  neutralized  ;  the 
results  are  chloride  of  potassium  and  chlorate  of  potassa.* 

Properties.  Chlorate  of  potassa  generally  occurs  in  four 
and  six-sided  crystalline  scales;  colorless,  and  of  a  pearly 
lustre ;  soluble  in  16  times  its  weight  of  water  at  60°,  and  in 
2J  of  boiling  water.  It  is  anhydrous,  and  fuses  at  400°  or 
500° ;  by  increase  of  temperature,  it  yields  pure  oxygen  gas. 

It  acts  very  energetically  upon  many  imflammable  bodies. 

Exp.  Put  2  grains  of  the  salt  into  a  mortar,  with  1  grain  of 
sulphur.  Mix  them  accurately,  and  then  strike  the  collected  mass 

*  For  other  processes,  see  Turner's  Chemistry. 


300  Salts.  —  Chlorates. 

forcibly  with  the  pestle  ;  a  loud  detonation  will  ensue.     Charcoal  will 
produce  a  similar  effect;  or, 

Ezp.  Instead  of  the  sulphur,  add  a  grain  of  phosphorus,  and  the 
detonation  will  be  much  louder.* 

Many  of  the  stronger  acids  decompose  this  salt. 

Exp.  Mix  2  parts  of  sugar  with  1  of  chlorate  of  potassa,  and  pour 
upon  it  a  few  drops  of  sulphuric  acid ;  the  decomposition  will  be  at- 
tended by  a  sudden  inflammation. 

Exp.  Put  2  parts  of  this  salt  with  I  of  phosphorus  into  a  wine- 
glass filled  with  warm  water,  and  then  pour,  by  means  of  the  dropping- 
tube,  strong  sulphuric  or  nitric  acids  directly  upon  the  salt;  the  phos- 
phorus will  ignite  under  the  water,  owing  to  the  development  of  oxy- 
gen from  the  decomposition  of  the  salt. 

Uses.  It  is  employed  in  the  preparation  of  percussion 
powder,  in  which  this  salt  is  substituted  for  nitre. 

Matches  are  also  made  by  first  dipping  them  in  melted  sul- 
phur, and  then  in  a  composition  of  chlorate  of  potassa,  sugar, 
gum  arabic,  and  vermilion. 

Lucifer  Matches  have  a  similar  composition. 

An  attempt  was  made  in  1788  to  substitute  chlorate  of 
potassa  for  nitre,  in  the  manufacture  of  gunpowder;  but, 
as  might  have  been  expected,  on  triturating  the  mixture, 
it  exploded  with  violence,  and  destroyed  several  of  the 
operators. 

A  few  grains  of  this  salt,  put  into  water  with  a  few 
drops  of  hydrochloric  acid,  form  a  convenient  bleach  in  ir 
liquor. 

Chlorate  of  Baryta  (BaO  +  CIO5.  152.12)  is  prepared  by 
digesting  for  a  few  minutes  a  concentrated  solution  of  rhlora 
of  potassa,  with  a  slight  excess  of  silicated  hydrofluoric  acid  ; 
the  alkali  is  precipitated  in  the  form  of  an  insoluble,  double 
hydrofluate  of  silica  and  potassa,  while  chloric  acid  remain-* 
in  the  solution.  The  liquid,  after  filtration,  is  neutralized 
by  carbonate  of  baryta,  which  throws  down  the  excess  of 
silicated  hydrofluoric  acid,  and  chlorate  of  baryta  remains 
in  solution. 

Properties.  It  yields,  on  evaporation,  crystals  in  the  form 
of  four-sided  prisms,  has  a  pungent  taste,  is  soluble  in  4  times 
its  weight  of  cold,  and  in  a  smaller  quantity  of  warm  water. 
It  is  employed  for  forming  chlorous  acid. 


*  The  hands  should  be  covered  with  gloves,  and  the  mortar  turned 
from  the  face. 


Per  chlorate*  —  lodates.  301 

6.  PERCHLORATES. 

The  neutral  protosalts  of  perchloric  acid  consist  of  1 
equiv.  of  acid  and  base,  as  is  expressed  by  the  formula 
MO -(-CIO7.  Most  of  the  salts  are  deliquescent,  very  solu- 
ble in  water,  and  soluble  in  alcohol.  When  heated  to  red- 
ness, they  yield  oxygen  gas  and  metallic  chlorides ;  and  they 
are  distinguished  from  the  chlorates  by  not  acquiring  a  yellow 
tint,  on  the  addition  of  hydrochloric  acid. — T. 

The  salts  are  formed  by  neutralizing  the  base  with  per- 
chloric acid,  excepting  perchlorate  of  potassa,  which  is 
formed  from  the  chlorate  by  heat  and  sulphuric  acid. 

7.     CHLORITES. 

The  alkaline  chlorites  are  formed  by  transmitting  a  current 
of  chlorous  acid  gas  into  a  solution  of  the  pure  alkalies ;  they 
are  remarkable  for  their  bleaching  and  oxidizing  properties. 

8.     HYPOCHLORITES. 

These  salts  may  be  formed  by  the  action  of  chlorine  gas  on 
the  alkaline  bases ;  the  most  important  of  these  is  the  hypo- 
chlorite  of  lime,  which  is  well  known  as  a  bleaching  powder. 

9.       lODATES. 

The  salts  of  iodic  acid  are  very  similar  in  character  to 
those  of  chloric  acid ;  in  all  the  neutral  protiodates,  the  oxy- 
gen of  the  base  and  acid  is  in  the  ratio  of  1  to  5 ;  the 
iodates  are  easily  recognized  by  the  action  of  de-oxidizing 
agents.  Thus  the  sulphurous,  phosphorous,  hydrochloric 
and  hydriodic  acids  deprive  the  iodic  acid  in  the  salt  of 
its  oxygen,  and  set  the  iodine  at  liberty.  None  of  the 
iodates  are  found  native ;  they  are  all  insoluble,  or  sparingly 
soluble  in  water,  excepting  the  iodates  of  the  alkalies. 

lodate  of  Potassa  (KO  +  IO5.  213.45)  may  be  obtained 
26 


302  Salts.  —  Pltosphates. 

by  adding  iodine  to  a  concentrated,  hot  solution  of  pure 
potassa,  until  the  alkali  is  completely  neutralized.  All  the 
insoluble  iodates  may  be  procured  from  this  salt ;  thus  the 
iodate  of  baryta  may  be  formed  by  mixing  chloride  of 
barium  with  a  solution  of  iodate  of  potassa. 

10.  The  Bromaies  are  very  similar  to  the  chlorates  and 
iodates. 

11.     PHOSPHATES. 

There  are  three  acids  of  phosphorus  which  are  isomeric  — 
the  phosphoric,  pyrophosphoric,  and  mr.taphosphoric ;  hence 
it  becomes  necessary  to  have  three  corresponding  families  of 
salts. 

I.  Phosphates.  All  the  neutral  protophosphates  are  solu- 
ble in  water,  and  redden  litmus  paper,  on  which  account  they 
are  called  super plwsphates. 

The  Tripfiosphatcs,  except  those  of  the  pure  alkalies,  are 
sparingly  soluble,  or  insoluble  in  water,  but  are  all  dissolved 
by  nitric  or  phosphoric  acids.  The  phosphates  and  diphos- 
phates  are  changed  by  heat  into  pyrophosphates  and  meta- 
phosphates;  the  phosphates  of  the  pure  alkalies  are  but  par- 
tially decomposed  by  heat  and  combustible  matter,  and  those 
of  baryta,  strontia,  and  lime,  undergo  no  change ;  but  most  of 
the  phosphates  of  the  second  class  of  metals  are  resolved  into 
hosphurcts  by  those  agents. 

The  insoluble  phosphates  are  decomposed  when  boiled 
with  a  strong  solution  of  carbonate  of  potassa,  or  soda. 

Triphosphate  of  Potassa  (3KO  +  P2O5.  212.85)  is  formed 
by  adding  caustic  potassa  in  excess  to  a  solution  of  phos- 
phoric acid. 

Diphosphate  of  Potassa  (2KO.2HO  +  P2O5.  165.7J  is  pre- 
pared by  neutralizing  the  superphosphate  of  lime  obtained 
from  bones,  with  carbonate  of  potassa. 

Phosphate  of  Potassa  (KO.2HO  +  P2O5.  136.55)  is  formed 
by  adding  phosphoric  acid  to  carbonate  of  potassa,  until  the 
liquid  ceases  to  give  a  precipitate  with  chloride  of  barium, 
and  then  setting  aside  to  crystallize. 


Phosphates.  303 

Triphosphatc  of  Soda.  3NaO-f-P2O5.  165.3;  in  crystals, 
with  24  equiv.  of  water,  ~3S  1.3.  This  salt  is  prepared  by 
adding  pure  soda  to  a  solution  of  the  succeeding  compound, 
until  the  liquid  feels  soapy  to  the  fingers;  the  solution  is  then 
evaporated  until  a  pellicle  forms;  on  cooling,  the  crystals 
which  are  deposited,  are  quickly  re-dissolved  in  water,  and  are 
crystallized. 

Properties.  Triphosphate  of  soda  crystallizes  in  colorless, 
six-sided,  slender  prisms,  which  have  an  alkaline  taste  and  re- 
action ;  soluble  in  five  times  their  weight  of  water  at  60°,  and 
in  still  less  of  hot  water;  the  crystals  undergo  watery  fusion 
at  170°,  but  are  not  decomposed  at  a  red  heat.  The  feeblest 
acid  deprives  the  salt  of  £  of  its  soda. 

Triphosphatc  of  Soda  and  Basic  Water.  2NaO.HO-f- 
P2O5.  143 ;  in  crystals,  with  24  equiv.  of  water.  =  359.  This 
salt  is  the  most  common  of  the  phosphates,  being  manufac- 
tured on  a  large  scale,  by  neutralizing,  with  carbonate  of 
soda,  the  acid  phosphate  of  lime,  which  is  procured  by  the 
action  of  sulphuric  acid  on  burned  bones. 

Properties.  It  crystallizes  in  oblique  rhombic  prisms, 
hence  called  rhombic  phosphate ;  its  crystals  are  always  alka- 
line to  test  paper;  effloresce  in  the  air  ;  soluble  in  four  times 
their  weight  of  cold,  and  twice  their  weight  of  warm  water. 

Acid  Triphosphate  of  Soda  and  Basic  Water  (NaO.2HO 
-|-  P-O\  120.7  ;  in  crystals,  with  2  eq.  water,  =  138.7)  is  com- 
monly called  the  biphosphate  of  soda,  and  may  be  formed  by 
adding  phosphoric  acid  to  a  solution  of  carbonate  of  soda, 
until  it  ceases  to  give  a  precipitate  with  chloride  of  barium. 
When  the  solution  is  concentrated,  it  yields  two  different 
kinds  of  crystals  without  varying  its  composition. 

Phosphate  of  Soda  and  Ammonia  (NaO.H3N-|-P2O5. 
119.85,  with  10  eq.  water  =.  209.85)  is  easily  prepared  by 
mixing  1  equiv.  of  hydrochlorate  of  ammonia,  and  2  equiv. 
of  the  rhombic  phosphate  of  soda  ;  each  being  previously 
dissolved  in  a  small  quantity  of  boiling  water. 

It  is  known  as  microcosmic  salt,  and  is  much  employed  as 
a  flux  in  experiments  with  the  blowpipe  ;  when  heated,  it 
parts  with  its  water  and  ammonia. 


304  Salts.  —  Phosphates. 

Diphosphate  of  Ammonia  (2H3N  +  P2O5.  105.7;  in  crys- 
tals, with  3  equiv.  water,  =  132.7)  is  prepared  by  adding  am- 
monia to  phosphoric  acid  until  a  precipitate  is  formed  ;  the 
primary  form  of  the  crystals  is  an  oblique  rhombic  prism. 

Phosphate  of  Ammonia  (IPN  +  PO5.  88.55;  in  crystals, 
with  3  equiv.  water,  =.  115.55)  is  formed  in  the  same  manner 
as  the  phosphate  of  potassa,  crystallizes  in  octohedrons  with 
a  square  base,  and  in  right  square  prisms. 

Bone  Phosphate  of  Lime  (8CaO  +  3PW.  442.2)  exists 
in  bones  after  calcination,  and  falls  as  a  gelatinous  precipitate, 
on  pouring  chloride  of  calcium  into  a  solution  of  rhombic 
phosphate  of  soda. 

Triphosphatc  of  Lime  (3CaO  +  paQ\  156.9)  occurs  in  the 
mineral  called  apatite. 

Diphosphate  of  Lime,  (2CaO  +  P2*)5  +  1  eq.  basic  water, 
=  137.4,)  commonly  called  neutral  phosphate,  falls  as  a  granu- 
lar precipitate,  when  the  rhombic  phosphate  of  soda  is  added, 
drop  by  drop,  to  chloride  of  calcium  in  excess. 

Phosphate  of  Lime  (CaO  +  P*O5  +  2  eq.  basic  water,  = 
117.9)  is  commonly  called  the  biphosphate,  from  its  acid  re- 
action, and  may  be  formed  by  dissolving  either  of  the  pre- 
ceding salts  in  a  slight  excess  of  phosphoric  acid  ;  it  exists  in 
urine. 

Diphosphate  of  Magnesia.    2MgO  +  FJO5.    112.8. 

Triphosphate  of  Magnesia.    3MgO  -|-  P2O5.    133.5. 

Phosphate  of  Ammonia  and  Magnesia  (2MgO  -(-  2H3N  -\- 
10HO  +  P-O5.  237.1)  subsides  as  a  pulverulent,  granular 
precipitate  from  neutral  alkaline  solutions,  containing  phos- 
phoric acid,  ammonia,  and  magnesia;  it  constitutes  a  variety 
of  urinary  concretions.- 

Triphosphate  of  Oxide  of  Silver  is  formed  when  the 
rhombic  phosphate  of  soda  is  mixed  in  solution  with  nitrate 
of  silver  ;  it  is  a  yellow  powder  when  dry  ;  on  exposure  to 
light,  it  is  speedily  blackened. 

II.    Pyrophosphates.     The  only  salts  of  this  family  which 
have  been  studied,  are  those  of  soda  and  oxide  of  silver. 
They  are  thus  constituted  :  — 


Arscniatcs.  305 

Dipyrophosphate  of  Soda.     2NaO  -|-  P2O5.  62.6  -f  71  .4  =  134. 

Dipyrophospkate  in  crystals,  with  10  eq.  water,  90  =  224. 

Acid  Dipyrophosphate  of  Soda  and  Basic  Water.     NaO.HO  -f-  P2O5  = 

Pijrophosphate  of  Soda.     NaO.P2O5.   31  .3  -f  71  .4  =  1  02.7. 
DijHjrophosphate  of  Oxide  of  Silver.    2AgO-fP2O\   232  +  71.4  = 
303.4.  /7^ 

III.  Mctaphosphates.  The  only  salts  of  this  family  yet 
examined  are  those  of  soda,  baryta,  and  oxide  of  silver. 

MctapkosphJe  of  Soda..  NaO  P'O5,  1  eq.  Na,  31.5  +  leq.  P2O5,  71.4 
=  102.7. 

M.tanhosphate  of  Baryta.  BaO.P2Os,  1  eq.  BaO,  767  -f  1  eq.  P2O3, 
71.4»  148.1. 

MHU  i,i,<>*  t,liate  of  Silver.  AgO.P2O5,  leq.  AgO,  116  -f  1  eq.  P!O5, 
71.4  =  187.4. 

SiLb-metiphosphate  of  Silver.  3AgO  -f2P2Oft,  3  eq.  AgO,  348-f2eq. 
142.8  =  490.8. 


12.    ARSENIATES. 

Arsenic  acid  resembles  the  phosphoric  in  composition, 
and  in  many  of  its  properties.  The  oxygen  of  the  oxide  and 
acid  in  their  salts  is  as  1  to  5;  salts  of  2  equiv.  of  basic 
water  are  soluble  in  water,  redden  litmus  paper,  and  are 
usually  considered  bisalts  ;  those  with  1  equiv.  of  basic 
water,  in  which  the  oxygen  of  the  base  and  acid  is  as  2  to 
5,  are  commonly  called  neutral  arseniates  ;  those  without 
water  are  described  as-  subarscniatcs.  This  acid  has  a  strong 
tendency  to  form  trisalts;  some  of  the  arseniates  bear  a  red 
heat  without  decomposition,  but  all  are  decomposed  when 
thus  heated  with  charcoal,  metallic  arsenic  being  set  at 
liberty. 

The  soluble  arseniates  are  easily  recognized  by  the  tests 
for  arsenic.  (See  p.  256.) 

The  insoluble  arseniates  are  tested  by  boiling  them  in  a 
strong  solution  of  the  fixed  alkaline  carbonates,  by  which 
they  are  deprived  of  their  acid  ;  the  acid  may  then  be  de- 
tected in  the  usual  way. 

The  following  are  the  principal  arseniates  :  — 

Triarseniate  of  Soda.  3NaO  -f  As2O5,  3  eq.  NaO,  93.7  +  1  eq. 
As205,  115.4  =  209.3. 

Do.  in  crystals  with  1  eq.  water  216  =  425.3. 

26* 


30C  Salts.  —  Arsenites. 

Diarseniate  of  Soda  and  Basic  Water.   2NaO  +  HO  +  AsK)5,  eq.  187. 

Acid  Arseniateof  Soda  and  Basic  Water.  JNaO  -j-  2HO  -j-  As'Oaq.  = 
JC4.7. 

Triarseniate  of  Potassa.  3KO  -|-  As»O»,  3  eq.  KO,  141 .454- 1  eq. 
As'OS  115.4  =  256.85. 

Diarseniate  of  Potassa.  SKO  +  AsK)5,  2  eq.  KO,  94.3  + 1  eq. 
As»0%  115.4  =  209.7. 

Arseniate.  of  Potassa.  KO.  AslO»,  1  eq.  KO,  47.15  +  1  eq.  As'O6, 
115.4  =  162.55. 

Diarseniate  of  Ammonia.  2H3N  4-  AsK)5,  2eq.  NH3  34.3+1  eq. 
As'O*,  115.4  ==149.7. 

Arseniate  of  Ammonia.  NH3,  AsK)4,  1  eq.  NH3,  17.554-1  eq. 
As'O5,  115.4  =  132.55. 

Triarseniate  of  Baryta.  3BaO  +  As'O6,  3  eq.  BaO,  230.1  +  1  eq. 
As'O4,  115.4=345.5. 

Diarseniate  of  Baryta.  2BaO+As»O6,  2  eq.  BaO,  153.4  +  1  eq. 
As«0»,  115.4  ==268.8 

Arseniate  of  Byrata.  BaO  +  As'O5,  1  eq.  BaO,  76.7  + 1  eq.  As'O4, 
115.4  =  192.1. 

Triarseniate  of  Lime.  3CaO-hA8«O*,  3  eq.  CaO,  85.5  +  1  eq. 
8«0>,  115.4  =  2()0.9. 

Diarseniate  of  Lime.  2CaO  +  As«O»,  2  eq.  CaO,  57  +  1  eq.  As'O*, 
115.4  =  172.4. 

Arseniate  of  Lime.  CaO  +  As'O*,  1  eq.  CaO,  26.5  +  1  eq.  As'O5, 
115.4  =  143.9. 

Triarseniate  of  Lead.  3PbO  +  As'O4,  3  eq.  PbO,  334.8  +  1  eq. 
As«0>,  115.4=450.2. 

Diarseniate  of  Lead.  2PbO+'A8>O4.  2  eq.  PbO,  223.2+1  eq. 
As*0»,  115.4  =  3384. 

Triarseniate  of  Ox-Silver.  2AgO  +  As«O*,  3  eq.  AgO,  348  +  1  cq. 
As«0»,  115.4  =  463.4. 


13.  ARSENITES. 

The  arsenites  of  potassa,  soda,  and  ammonia,  may  be 
prepared  by  acting  with  those  alkalies  on  arsenious  acid. 

They  are  very  soluble  in  water,  and  have  an  acid  re-action. 

Most  of  the  other  arsenites  are  insoluble  or  sparingly  solu- 
ble in  water,  but  are  dissolved  by  an  excess  of  arsenious, 
nitric,  and  most  other  acids,  with  which  their  bases  do  not 
form  insoluble  compounds. 

They  are  all  decomposed  when,  heated  in  close  vessels. 

The  soluble  salts,  if  neutral,  are  characterized  by  forming 
a  yellow  arseniate  of  oxide  of  silver,  when  mixed  with  nitrate 
of  silver,  and  a  green  arsenite  of  protoxide  of  copper  — 
Scheele's  green  —  with  sulphate  of  copper. 

The  arsenite  of  potassa  is  the  active  principle  in  Fowler's 
arsenical  solution. 


Chromates  —  Borates.  307 

14.  CHROMATES. 

The  chromates  may  generally  be  known  by  (heir  yellow 
or  red  color.  They  may  be  known  chemically  by  the  green 
solution  of  chloride  of  chromium,  formed  by  boiling  any 
chromate  with  hydrochloric  acid  mixed  with  alcohol.  They 
are  all  decomposed  by  heat  and  combustible  matter. 

Chromate  of  Potassa  (KO  +  CrO3.  99.15)  is  formed  by 
heating  to  redness-  the  native  oxide  of  chromium  and  iron 
(chromate  of  iron)  with  nitrate  of  potassa,  when  chromic  acid 
is  generated,  and  unites  with  the  alkali  of  the  nitre. 

Properties.  Taste  cool,  bitter,  and  disagreeable,  soluble 
in  boiling  water,  and  insoluble  in  alcohol. 

Bichromate  of  Potassa  (KO  +  2CrO3.  "151.15)  is  of  great 
importance  in  dyeing.  It  is  prepared  by  acidulating  the 
neutral  chromate  with  sulphuric,  or,  still  better,  with  acetic 
acid,  and  allowing  the  solution  to  crystallize  by  spontaneous 
evaporation. 

Properties.     When    slowly    formed,    four-sided    rhombic 
prisms  are   deposited,  which  are  anhydrous,  and  of  a  rich 
red  color ;  soluble  in  10  times  their  weight  of  water  at  60° 
and  the  solution  reddens  litmus. 

The  insoluble  chromates,  such  as  those  of  baryta,  zinc, 
lead,  mercury,  and  silver,  are  prepared  by  mixing  the  soluble 
salts  of  those  bases  with  a  solution  of  chromate  of  potassa. 

Chromate  of  Lead.  PbO  +  CrO3.  1G3.6.  This  is  the 
yellow  chromate,  and  is  extensively  used  as  a  pigment. 
Chromate  of  oxide  of  zinc  may  be  used  for  the  same  purpose. 

15.  BORATES. 

The  boracic  is  a  feeble  acid,  and  neutralizes  imperfectly ; 
hence  the  borates,  such  as  soda,  potassa,  and  ammonia,  have 
an  alkaline  re-action ;  hence,  also,  the  more  powerful  acids 
separate  the  alkali  from  boracic  acid,  although,  at  a  red  heat, 
boracic  acid,  owing  to  its  fixed  nature,  decomposes  every  salt 
whose  acid  is  volatile.  The  borates  of  the  alkalies  are  solu- 


308  Salts.  —  Carbonates. 

ble  in  water,  but  most  of  the  other  borates  are  sparingly 
soluble  ;  they  are  not  decomposed  by  heat,  though  remark- 
able for  their  fusibility.  They  are  distinguished  by  the 
following  character  :  — 

By  digesting  any  borate  in  an  excess  of  strong  sulphuric 

acid,   evaporating   to   dryness,    and   boiling   the  residue    in 

'strong  alcohol,  the  solution  will  burn  with  n  green  fl 


Biboratc  of  Soda,  (2BO3  -|-  NaO.  191.1  ;  in  crystals,  with 
10  equiv.  of  water,  =  101.01,)  commonly  called  borax,  oc- 
curs native  in  certain  lakes  in  Thibet.  It  is  imported  from 
India  under  the  name  of  lineal,  which,  after  purification, 
constitutes  the  refined  borax  of  commerce. 

Properties.  It  crystallizes  in  hexahedral  prisms.  w  The 
crystals  are  efflorescent  ;  when  heated,  they  lose  their  water 
of  crystallization,  fuse,  and  form,  on  cooling,  a  crystalline 
mass,  called  glass  of  borax. 

Borax  is  much  used  as  a  flux  for  welding  iron  and  steel. 

Boracite  is  a  biborate  of  magnesia. 

A  new  biborate  of  soda  has  been  lately  described  ;  better 
as  a  flux,  for  the  use  of  jewellers,  than  the  preceding. 

16.  '.CARBONATES. 

The  carbonates  are  distinguished  from  all  other  salts,  by 
being  decomposed  with  effervescence,  owing  to  the  escape 
of  carbonic  acid  gas,  by  nearly  all  acids. 

All  the  carbonates,  except  those  of  potassa,  soda,  and  lithia, 
are  decomposed  by  heat;  and  all,  except  those  of  potassa, 
soda,  and  ammonia,  are  of  sparing  solubility  in  pure  water  ; 
but  all  are  soluble  in  excess  of  carbonic  acid.  Several  of 
them  occur  native. 

Carbonate  of  Potassa  (KO  +  CO2.  69.27)  is  procured  by 
lixiviating  the  ashes  of  land  plants,  and  boiling  the  lye  —  a 
process  which  is  performed  on  a  large  scale  in  Russia,  and 
in  this  country"  This  is  the  impure  carbonate  of  commerce, 
known  by  the  names  potash  and  prnr/ash,  and  is  of  great  utili- 
ty in  the  arts,  especially  in  the  manufacture  of  soap  and  glass. 
As  thus  prepared,  it  always  contains  other  compounds,  such 


Carbonates.  309 

as  sulphate  of  potassa,  and  chloride  of  potassium.  For 
chemical  purposes,  it  is  obtained  by  heating  cream  of  tartar 
to  redness,  when  the  acid  is  decomposed,  and  a  pure  car- 
bonate of  potassa  mixed  with  charcoal  remains.  The  char- 
coal is  removed  by  solution  in  water,  and  evaporation. 

Properties.  Taste  strongly  alkaline,  and  slightly  caustic; 
changes  the  vegetable  purple  colors  to  green ;  soluble  in  less 
than  an  equal  weight  of  water  at  60°;  deliquesces  on  ex- 
posure to  the  air;  is  insoluble  in  pure  alcohol,  and  fuses  at 
a  full  red  heat,  but  undergoes  no  other  change. 

Bicarbonate  of  Potassa  (KO  +  2CO2.  91.39;  in  crystals, 
with  1  equiv.  water,  =  100.39)  is  made  by  transmitting  a 
current  of  carbonic  acid  gas  through  a  solution  of  the  car- 
bonate. This  salt  is  milder  than  the  carbonate,  into  which 
it  is  converted  by  a  low  red  heat.  It  does  not  deliquesce  on 
exposure,  and  requires  four  times  its  weight  of  water  at  60° 
for  solution. 

Carbonate  of  Soda  (NaO  +  CO2.  53.42;  in  crystals,  with 
10  equiv.  water,  =  143.42)  is  obtained  from  the  ashes  of  sea- 
weeds, in  the  same  manner  as  carbonate  of  potassa.  The 
best  variety  of  the  impure  salt  is  the  barilla,  which  con- 
sists of  the  semifused  ashes  of  the  salsola  soda,  a  plant  culti- 
vated on  the  Mediterranean  shores  of  Spain.  Kelp  is  another 
variety,  and  formed  from  the  sea-weeds  on  the  northern 
shores  of  Scotland. 

Properties.  Crystallizes  in  rhombic  prisms  ;  effloresces, 
and  dissolves  in  its  water  of  crystallization  when  heated,  and 
becomes  anhydrous  by  continued  heat ;  soluble  in  about  2 
parts  of  cold,  and  in  less  than  its  weight  of  boiling  water. 

Bicarbonate  of  Soda  (NaO  +  2CO2.  75.54  ;  in  crystals, 
with  1  equiv.  water,  =  84.54)  is  formed  by  the  same  process 
as  the  bicarbonate  of  potassa,  and,  like  that  salt,  is  much 
milder  than  the  carbonate. 

Sesquicarbonate  of  Soda  (2NaO  +  3CO2.  4HO.  164.96) 
is  found  native  in  Africa,  on  the  banks  of  soda  lakes,  and  is 
called  trona. 

Carbonate  of  Ammonia  (H3N  +  CO2.  39.27)  is  obtained 
by  mixing  dry  carbonic  acid  over  mercury,  with  twice  its 
volume  of  ammoniacal  gas.  It  is  a  dry,  white  powder,  and 


31 0  Salts.  —  Carbonates. 

has  an  alkaline  re-actiou  ;  its  odor  is  pungent,  resembling 
ammonia. 

Bicarbonate  of  Ammonia  (H3N.2HO  +  2CO2.  79.39)  is 
obtained  by  transmitting  a  current  of  carbonic  acid  gas 
through  a  solution  of  carbonate  of  ammonia,  and  evaporating 
the  solution  by  gentle  heat.  It  is  deposited  in  right  rhom- 
bic prisms  ;  inodorous,  and  nearly  tasteless. 

Sesguicarbonate  of  Ammonia  (2H3N.2HO2  +  3CO2. 
118.60)  is  prepared  by  heating  1  part  of  hydrochlorate  of 
ammonia,  mixed  with  1J  of  carbonate  of  lime,  carefully 
dried. 

The  chloride  of  calcium  remains  in  the  retort,  and  this 
suit  is  sublimed;  it  is  hard,  compact,  translucent,  of  a  crys- 
talline texture,  and  ammoniacal  odor. 

Carbonate  of  Baryta  (BaO  +  CO2.  98.82)  occurs  native 
in  the  mineral  Witherite.  It  may  be  prepared  by  mixing  a 
soluble  salt  of  baryta  with  any  of  the  alkaline  carbonates. 

Properties.  This  salt  is  anhydrous,  very  insoluble,  and 
highly  poisonous. 

Carbonate  of  Strontia  (SrO  -(-  CO2.  73.92)  is  known  by 
the  name  of  strontianite ;  it  may  be  prepared  in  the  same 
manner  as  carbonate  of  baryta ;  it  is  soluble  in  excess  of 
carbonic  acid. 

Carbonate  of  Lime  (Ca-)-CO2.  50.62)  is  a  very  abundant 
natural  production,  occurring  under  a  great  variety  of  forms, 
such  as  limestone,  marble,  chalk,  Iceland  spar,  etc.;  often 
in  regular  crystals.  Carbonic  acid  and  lime  have  a  strong 
affinity  for  each  other  ;  and  hence  moist  lime,  or  lime  in  so- 
lution, when  exposed  to  the  air,  absorbs  the  acid  contained 
in  the  atmosphere,  and  carbonate  of  lime  is  formed.  It  is 
sparingly  soluble  in  water,  but  soluble  in  excess  of  carbonic 
acid;  the  crust  formed  on  the  top  of  lime  water  is  car- 
bonate of  lime. 

Carbonate  of  Magnesia  (MgO  +  CO2.  42.82;  in  crystals, 
with  3  equiv.  of  water,  ^r  69.82)  is  found  native  in  the  mine- 
ral called  magnesite,  which  is  nearly  pure  anhydrous  car- 
bonate of  magnesia.  It  is  obtained  in  minute,  transparent, 


Carbonates.  311 

hexagonal  prisms,  when  a  solution  of  the  bicarbonate  evapo- 
rates slowly  in  an  open  vessel ;  the  crystals  lose  their  water, 
and  become  opaque  by  a  very  gentle  heat,  and  even  in  dry 
air,  at  60°.  They  are  decomposed  by  water. 

A  Carbonate  of  Magnesia,  consisting  of  4  equiv.  of  water, 
3  of  acid,  and  4  of  magnesia,  falls  as  a  white  powder  when 
carbonate  of  potassa  is  added  to  a  hot  solution  of  sulphate 
of  magnesia;  this  salt  is  very  insoluble,  requiring  9000  parts 
of  hot  water  for  solution. 

Carbonate  of  Protoxide  of  Iron  (FeO  +  CO2.  ,58. 12)  is  a 
very  abundant  natural  production,  occurring  either  in  masses, 
or  in  rhombohedrons.  It  exists  also  in  most  of  the  cha- 
lybeate mineral  waters.  It  may  be  formed  by  mixing  an 
alkaline  carbonate  with  sulphate  of  protoxide  of  iron.  It 
acts  as  a  tonic  upon  the  animal  system. 

Bicarbonate  of  Protoxide  of  Copper  (2CuO  -f  Co2.  101.32) 
is  found  native  as  a  hydrate,  in  the  mineral  called  malachite, 
of  a  beautiful  green  color. 

It  may  be  obtained  by  precipitation  from  a  hot  solution  of 
sulphate  of  protoxide  of  copper,  by  carbonate  of  soda  or  po- 
tassa ;  this  is  the  mineral  green  of  painters. 

When  the  hydrate  is  boiled  for  a.  long  time  in  water,  it 
loses  both  carbonic  acid  and  combined  water,  and  the  color 
changes  to  a  brown. 

The  blue  copper  ore,  and  the  blue  pigment  called  verditer* 
have  a  similar  composition. 

Carbonate,  of  Protoxide  of  Lead  (PbO  +  CO1.  133.72)  is 
the  white  lead  of  painters.  It  occurs  native  in  white  pris- 
matic crystals.  As  an  article  of  commerce,  it  is  prepared 
from  the  subacetate  by  a  current  of  carbonic  acid ;  also  by 


*  Refiners'  Verditer,  made  by  silver  refiners,  is  composed  of  3  equiv. 
of  oxide  and  4  of  carbonic  acid.  « 

A  very  good  verditer  is  formed  by  adding  a  quantity  of  lime  to  ni- 
trate of  copper  sufficient  to  throw  down  the  oxide.  The  green  precip- 
itate must  be  washed,  and  nearly  dried  upon  a  strainer.  If  it  is  then 
mixed  with  10  per  cent,  of  fresh  lime,  the  color  will  become  blue.  It 
must  now  be  dried,  and  is  then  fit  for  use. 


312  Salts.  —  Double  Carbonates  —  Silicates. 

exposing  metallic  lead  in  minute  division  to  air  and  moisture, 
or  by  the  action  of  the  vapor  of  vinegar  on  thin  sheets  of 
lead. 

Dicarbonate  of  Peroxide  of  Mercury,  2HgO--f-CO2. 
458.12.  When  a  solution  of  the  nitrate  of  peroxide  o^ 
mercury  is  decomposed  by  carbonate  of  soda,  this  salt  falls 
as  an  ochre-yellow  precipitate. 


17.   DOUBLE  CARBONATES^  • 

The  most  remarkable  of  these  salts  is  the  double  carbovat, 
of  lime  and  magnesia,  (MgO.CO^+CaO.CO2.  93.44,)  form- 
ing the  minerals  called  dolomite,  bitter  spar,  and  pearl  spar. 

The  rock  called  magnesian  limestone  is  an  impure  variety 
of  dolomite. 

Barytocalcite  is  a  double  carbonate  of  baryta  and  Ihnr. 
CaO.COs  +  BaO.CO'.  149.44. 

Carbonate  of  Soda,  fused  with  the  carbonate  of  bant  -, 
strontia,  or  lime,  in  the  ratio  of  their  equiv.,  yields  cry-i  :!- 
line,  definite  compounds.  In  the  same  manner,  also,  sulphate 
of  soda,  heated  with  the  above  carbonates,  yields  double 
salts,  which  are  very  similar. 

18.   SILICATES. 

Silicic  Acid  is  one  of  the  most  powerful  acids.  The  snlis 
which  it  forms,  although  very  numerous  and  important  com- 
pounds, have  not  hitherto  been  fully  investigated.  The  sili- 
cates are  remarkable  for  their  great  variety  of  composition  ; 
they  are  composed  of  from  1  equiv.  of  base  and  6  of  silicic 
acid  to  1  of  acid  and  3  of  base.  Those  most  frequently  met 
with  are, — 

1.  Simple  Silicates,  or  those  composed  of  1  equiv.  of  base 
and  1  of  silicic  acid.     These  are  a  very  numerous  class  of 
natural  compounds,  as,  silicate  of  manganese,  zinc,  glucina, 
cerium,  zirconia,  iron,  &c. 

2.  Bisilicates,  in  which  2  equiv.  of  silicic  acid  are  com- 


Silicates.  313 

bined  with  1  of  base.  There  are  many  native  compounds 
of  this  order  :  tabular  spar  is  a  bisilicate  of  lime ;  bottle 
glass  is  another  example. 

3.  Trisilicates,  in  which  3  equiv.  of  silicic  acid  are  united 
to  1  of  base.     The  most  important  of  the  bisilicates  is  plas- 
tic clay,  which  is  a  trisilicate  of  alumina. 

4.  Quadrisilicates,  which    are  principally  artificial  com- 
pounds, among  which  are  crown  glass,  French  window  glass, 
flint  glass,  and  enamel. 

In  addition,  it  should  be  remarked,  that  there  are  a  very 
great  number  of  simple  minerals,  which  are  composed  as 
above,  or  by  the  union  of  silicic  acid  with  other  acids  and 
with  bases.  In  fact,  the  greater  portion  of  the  crust  of  the 
globe  is  composed  of  silicates.  The  soils,  rocks,  and 
mountains,  are  but  masses  of  silicates. 

The  silicates  are  all  fusible  before  .the  compound  blow- 
pipe, and  all,  except  those  of  magnesia  and  alumina,  in  a 
forge  fire.  Those  of  2  or  more  bases  are  most  easily  fused; 
and  those  of  fusible  bases  are  more  easily  melted  than  those 
whose  bases  are  more  refractory. 

In  the  separation  of  the  metals  from  their  ores,  such  mat- 
ters are  added  as  will  form  with  the.  earthy  parts  of  the  ores 
fusible  silicates.  These  float  like  glass  on  the  surface  of  the 
reduced  metal,  and  are  easily  removed. 

All  kinds  of  glass  are  formed  by  heating  siliceous  sand 
with  alkaline  carbonates.  When  heat  is  applied,  the  alkali 
melts,  anil  the  sand  (silicic  acid)  combines  with  the  alkali, 
while  the  carbonic  acid  escapes  in  the  form  of  a  gas,  causing 
the  mass  to  swell  to  twice  its  former  bulk.  When  the  car- 
bonic acid  all  escapes,  the  mass  subsides,  and  is  called  frit. 
This  is  then  put  into  a  refractory  vessel,  and  placed  in  a 
furnace,  where  it  is  heated  until  it  is  melted  and  becomes 
glass.  (See  page  213.) 

The  silicates  are  all  insoluble,  excepting  those  of  potassa 

and  soda.     Those  compounds  formed  by  the  union  of  1  or 

2  equiv.  of  silicic  acid  are  more  soluble  than  those  of  3  or 

4.     The  double  silicates  of  these  alkalies,  that  is,  the  union 

24 


314  Salts.  —  Hydro-Salts. 

of  another  acid  or  base,  renders  the  compounds  still  less 
soluble. 

The  silicate  of  alumina  and  soda,  which  is  combined  with 
sulphuret  of  sodium  in  lapis  lazuli,  is  used  by  painters,  under 
the  name  of  ultramarine,  and  is  a  very  important  compound 

The  silicates  are  the  most  ^important  chemical  com 
pounds ;  forming,  as  they  do,  almost  the  entire  mass  of  the 
soil  in  every  country,  their  influence  upon  vegetation  is  con- 
stant and  universal.  To  the  agriculturist  they  are  com- 
pounds of  great  interest,  and  should  be  made  the  subjects 
of  intense  study. 

SECTION  3. 

ORDER  II.  —  HYDRO-SALTS. 

This  order  includes  those  salts  the  acid  or  base  of  which 
contains  hydrogen.  The  salts  formerly  called  muriates  or 
hydrochlorates  of  metallic  oxides,  are  now  generally  de- 
scribed as  chlorides  of  those  metals,  and  also  the  salts  of 
hydriodic  and  most  other  hydracids.  The  only  salts  whirh 
are  included  in  this  order  are  formed  by  the  hydracids  with 
ammonia  and  phosphurrtcd  hydrogen. 

Hydrochlorate  of  Ammonia.  IPN  +  HCL.  53.57.  This 
is  the  sal  ammoniac  of  commerce,  and  was  formerly  imported 
from  Egypt,  where  it  was  prepared  from  the  soot  of  camels' 
dung  by  sublimation ;  but  it  is  now  formed  by  several  pro- 
cesses. The  most  usual  is  to  decompose  the  sulphate  of  am- 
monia* by  the  chloride  of  sodium  or  magnesium. 

It  occurs  native,  in  masses  and  in  crystals,  in  the  vicinity 
of  volcanoes. 

Process.  It  may  be  produced  directly,  by  introducing 
liquid  ammonia  into  one  retort,  (see  Fig.  54,  p.  113,)  and 
HCL  into  the  other,  and  apply  heat.  As  the  two  gases  pass 


*  This  sulphate  is  obtained  by  digesting  with  gypsum  the  impure 
carbonate  of  ammonia,  procured  from  the  destructive  distillation  of 
bones  and  other  animal  substances,  so  as  to  form  an  insoluble  carbonate 
of  lime  and  a  soluble  sulphate  of  ammonia. 


Hydro-Salts.  315 

into  the  receiver,  a  white  cloud  appears,  which  is  hydrochlo- 
rate  of  ammonia  in  fine  powder. 

Properties.  This  salt  has  a  pungent,  saline  taste,  and  is 
insoluble  in  water  and  in  alcohol ;  it  sublimes  at  a  tempera- 
ture below  that  of  ignition,  without  fusion  or  decomposi- 
tion. 

Uses.  Used  in  the  arts  for  a  variety  of  purposes,  in  tin- 
ning copper,  to  prevent  oxidation,  and  by  dyers. 

When  dissolved  in  nitric  acid,  it  forms  the  aqua  regia, 
which  is  employed  for  dissolving  gold,  instead  of  nitro- 
hydrochloric  acid. 

Hijdriodate  of  Ammonia  (H3N.HI.  144.45)  is  a  white  powder,  very 
soluble  and  deliquescent. 

Hydrobromate  of  Ammonia  (FPN.HBr.  96.55)  is  a  white  anhy- 
drous salt. 

Hmlrofluate  of  Ammonia.  H3N.HI.  36.83.  See  Turner,  5th  edit, 
p.  469. 

Hydrosulphate  of  Ammonia  (H3N-|-HS.  34.25)  is 
formed  by  heating  a  mixture  of  1  part  of  sulphur,  2  of  sal- 
ammoniac,  anji  2  of  unslacked  lime.  It  is  used  as  a  re- 
agent, and  for  this  purpose  it  is  formed  by  saturating  a 
solution  of  ammonia  with  hydrosulphuric  acid. 

Hydrocyanate  of  Ammonia.     H3N  -|-  HC2N.    44.54. 

Hydrosulpkocyanatc  of  Ammonia.  H3N-f-HCyS9.    76.74. 

Trifluoboratc  of  A  mmonia.     3H3N  +  BF3.    1 18.39. 

Dljluobor ate  of  Ammonia.     2H3N-f-BF3.    101.24. 

Fluoborate  of  A  mmonia.     H3N  -f  BF3.   84.09. 

Fluosilicate  of  Ammonia.     H3N  +  SiF.   '43.33. 

Carbosulphate  of  Ammonia.     H3N  +  CS^.    55.47.* 

Salts  of  Phosplmreted  Hydrogen. 

Phosphureted  Hydrogen  resembles  ammonia  in  composi- 
tion, and  in  some  of  its  properties;  it  is  a  feeble  alkaline 
base,  and  combines  with  some  of  the  hydracids.  The  salt 

*  See  Turner,  5th  edit.  p.  4C9. 


316  Salts.  —  Sulphur-Salts. 

best  known  is  the  hydriodate  of  phosphureted  hydrogen, 
which  is  composed  of  127.3  parts  or  1  eq.  acid,  and  34.4 
parts  or  1  eq.  base,  and  crystallizes  in  cubes. 


SECTION  4. 

ORDER    III.  — SULPHUR-SALTS. 

The  sulphur-salts  are  double  sulphurets,  just  as  the  oxy- 
salts  are  double  oxides. 

The  sulphur-salts,  with  two  metals,  are  so  constituted,  that 
if  the  sulphur  in  each  were  replaced  by  an  equivalent  quan- 
tity of  oxygen,  it  would  form  an  oxy-salt. 

The  close  analogy  between  the  two  orders  of  salts  appears 
also  from  the  fact,  that  hydrosulphuric  and  hydrosulphocy- 
anic  acids  unite  both  with  ammonia  and  sulphur  bases. 

The  principal  sulphur  bases  are  the  protosulphurets  of 
potassium,  sodium,  lithium,  barium,  strontium,  calcium, 
magnesium,  and  the  hydrosulphate  of  ammonia ;  and  the 
sulphur  acids  are  the  sulphurets  of  arsenic,  antimony,  tung- 
sten, molybdenum,  tellurium,  tin,  and  gold,  together  with 
hydrosulphuric  acid,  bisulphuret  of  carbon,  and  sulphuret  of 
selenium. 

The  sulphur-salts  are  divided  into  families  which  contain 
the  same  sulphur  acid ;  the  generic  name  of  each  family  is 
formed  from  the  sulphur  acid  terminated  with  sulphur (t ; 
thus  the  'salts  which  contain  persulphuret  of  arsenic  or 
hydrosulphuric  acid,  as  the  sulphur  acid,  are  termed  arsenio- 
sulphurcts  and  hydrosulphurcts,  and  a  salt  composed  of  those 
sulphur  acids,  with  sulphuret  of  potassium,  is  termed  arsrnio- 
sulphurct,  and  hydro  sulphuret  of  sulphuret  of  potassium,  or 
simply  hydrosulphurct  of  potassium  * 


*  Ifr.  Hare  has  adopted  a  method  of  naming  the  sulphur-salts, 
founded  on  the  nomenclature  of  the  ozy-salts.  He  calls  the  electro- 
negative sulphuret  an  acid,  and  forms  its  name  by  changing  the  termi- 
nation of  the  element  with  which  the  sulphur  is  combined  into  ic,  and 


Sulphur ets.  317 


1.    HYDRO-SULPHURETS. 

The  salts  of  this  family  have  hydrosulphuric  acid  for  their 
electro-negative  ingredient;  most  of  them  are  soluble  in 
water,  are  decomposed  by  exposure  to  the  air  and  by  acids. 

Hydro-sulphurct  of  Potassium.     KS  -|-  HS.    72.35. 

The  anhydrous  salt  may  be  obtained  by  heating  to  low 
redness  anhydrous  carbonate  of  pot  issa  in  a  tubulated  retort, 
through  which  a  current  of  hydrosulphuric  acid  is  transmit- 
ted. It  forms,  when  cold,  a  white,  crystalline  solid.  The 
hydrous  salt  has  an  acrid,  alkaline,  and  bitter  taste. 

Jfydro-wlphuret  of  Sodium.     NaS  +  HS.    56.5. 

Hydro-sulphur  tt  of  Lithium.     LS  -j-  HS.    43.2. 

Hydrti'sulphuret  of  Barium  (BaS  -f-  HS.  101.9)  is  formed 
by  the  action  of  hydrosulphuric  acid  on  a  solution  of  baryta, 
excluded  from  the  air.  It  crystallizes  in  four-sided  prisms, 
and  is  very  soluble. 

Hydro-sulphuret  of  Strontium.     SrS  -f-  IIS.    Eq.  77. 

Hydro-sulphurct  of  Calcium.     CaS  +  HS.    Eq.  53.7. 

Hydro-sulphurct  of  Magnesium.     MgS  -\-  HS.    Eq.  45.9. 


2.    HYDRO-SULPHOCYANURETS. 

The  acid  of  these  salts  is  the  hydrosulphocyanuric  acid. 

Hydro-sulphon/anurct  of  Potassium  (KS-fHCyS2.  1 14.84) 
is  a  white,  crystalline  solid,  soluble  in  water  and  in  alcohol. 

Hydro-sulphocyanurrt  of  Hydrosulphate  of  Ammonia 
(H3N  +  HS)  +  (HCyS2.  93.84)'  exists  in  long,  brilliant  crys- 
tals, of  a  lemon-yellow  color. 


3.    CARBO-SULPHURETS. 

The  acid  of  this  family  is  the  bisulphuret  of  carbon. 

Carbo-sulpJiurtt  of  Potassium  (KS  +  CS2.  93.57)  is  pre- 
pared by  agitating  bisulphuret  of  carbon  with  a  strong  alco- 
holic solution  of  protosulphuret  of  potassium.  The  liquid, 
when  set  at  rest,  separates  into  three  layers,  the  lowest  of 
which  is  the  carbo-sulphuret  of  potassium.  On  evaporation, 

prefixing  sulph  or  sulpha.  Thus,  persulphuret  of  arsenic  he  calls  sulpft- 
arsenic  acid,  and  its  sulphur  salts,  sulpharseniates.  Hydrosulphuric  acid 
he  denominates  sulphydric  acid,  and  its  salts  sulphydrat es  ;  so  of  the  rest. 

27* 


318  Salts.  —  Molybdo-sulphurets. 

a  deliquescent,  yellow,  crystalline  salt  is  deposited,  sparingly 
soluble  in  alcohol. 

The  Carbo-sulphuret  of  Sodium  (NaS  +  CS2.  77.72)  and 
the  Carbo-sulphuret  of  Lithium  (LS  -\-  CS2.  G4.42)  are  simi- 
lar to  the  preceding. 

Carbo-sulphuret  oftfa  Hydrosulphate  of  Ammonia  (H3N. 
HS  +  CS2.  72.57)  is  a  very  volatile  salt,  and  must  be  kept 
in  bottles  tightly  corked.  Exposed  to  the  air,  it  absorbs 
water  and  becomes  red.* 


4.   ARSENIO-SULPHURRTS. 

Each  of  the  three  sulphurets  of  arsenic  is  capable  of  acting 
as  a  sulphur  acid  ;  giving  rise  to- three  distinct  families  of 
sulphur  salts,  arsenio-protosulphurets,  arsenio-sesquisulphttn  f.<t 
and  arscnio-persulphurets.  The  persulphuret  of  arsenir  i.< 
the  most  powerful  of  these  acids.  The  arsenio-persulphurets 
of  the  alkalies  and  alkaline  earths,  are  very  soluble  in  v 
have  a  lemon-yellow  color  when  anhydrous,  but  colorless 
when  combined  with  water  of  crystallization,  or  in  solution ; 
but  those  of  the  second  class  of  metals  are  generally  in- 
soluble. 

5.    MOLYBDO-SULPHURETS. 

The  acid  in  this  family  is  the  tersulphuret  of  molybdenum. 
The  most  remarkable  of  these  salts  is 

Molybdo-sulphurct  of  Potassium,  (KS  +  MoS3.  151.23,) 
which  is  formed  by  decomposing  a  solution  of  molybdate  of 
potassa  with  hydrosulphuric  acid  ;  on  evaporation,  beautiful 
crystals  with  four  and  eight  sides  are  deposited.  Berzelius  de- 
scribes this  compound  as  the  most  beautiful  which  chemistry 
can  produce.  The  crystals,  by  transmitted  light,  are  ruby- 
red,  and  their  surfaces,  while  moist,  and  also  the  solution 
which  yields  them,  shine  like  the  wings  of  certain  insects, 
with  a  metallic  lustre,  of  a  rich  green  tint. 


*  The  carbo-sulphuret  of  barium,  (B&S  -f-  CS*.  123.12,)  the  carbo-sul- 
phuret  of  strontium,  (SrS-J-CS'.  98.22,)  and  the  carbo-sulphuret  of  ail  c  hi  m , 
(CaS  -f-  CS*.  74.92,)  may  be  obtained  by  acting  on  bisulphurct  of  car- 
bon with  a  solution  of  the  protosulphurete  of  these  metals.  The  solu- 
tions are  orange  or  brown,  and*  the  crystals,  when  dry,  are  of  a  citron- 
yellow  color.  Carbo-sulphuret  of  magnesium.  MgS-^j-CS8.  67.12. 


Haloid  Salts.  319 


6.    ANTIMONIO-SULPHURETS. 

The  acid  of  this  family  is  the  sesquisulphuret  of  antimony, 
and  the  only  salt  examined  is  the  antimonio-sulphurct  ofpo- 
tassium,  which  may  be  formed  by  mixing  2  parts  of  car- 
bonate ofpotassa,  4  of  sesquisulphuret  of  antimony,  and  1  of 
sulphur,  and  fusing  the  mixture. 

7.     TuNGSTO-SULPHURETS. 

The  best  known  of  this  family  is  potassium.  When  a 
solution  of  tungstate  of  potassa  is  decomposed  by  hydrosul- 
phuric  acid,  and  the  solution  evaporates,  anhydrous,  quadri- 
lateral, flat  prisms  are  deposited,  of  a  pale-red  color,  which  is 
the  tungstosulphuret  of  potassium.  This  salt  unites  with 
tungstate  of  potassa  as  a  double  salt. 


SECTION  5. 

ORDER    IV.— HALOID   SALTS. 

This  order  includes  substances  composed,  like  the  pre- 
ceding salts,  of  bi-elementary  compounds,  one  or  both  of 
which  are  analogous  to  sea-salt  in  composition.  The  haloid 
acids  belong  generally  to  the  electro-negative,  and  the  haloid 
bases  to  the  electro-positive  metals. 

The  following  are  the  principal  groups  or  families  :  ^— 

1.  Hydrar go-chlorides.     The  haloid  acid  is  the  bichloride 
of  mercury  ;  they  are  obtained  by  mixing  their  ingredients  in 
the  ratio  of  combination,   and  setting  aside  the  solution  to 
crystallize. 

2.  Auro-chlorides.     The  acid  in    this  family   is  the  ter- 
chloride  of  gold  ;  they  are  prepared  like  the  preceding;  most 
of  them  have  an  orange,  or  a  yellow,  color. 

3.  P latino-chlorides.     The  haloid  acids  in  this  family  are 
the  protochloride  and  bichloride,  of  platinum. 

4.  Palladio-chlorides  are  salts  in   which  the  chlorides  of 
palladium  act  as  haloid  acids,  combining  with  many  of  the 
metallic  chlorides. 


320  Salts.  —  Haloid  Salts. 

5.  Rhodio-chlorides  are  formed  by  the  action  of  sesqui- 
chloride  of  rhodium  on  the  chlorides  of  potassium  and  so- 
dium. 

6.  The  Chlorides  of  Iridium  and  Osmium  are  the  haloid 
acids  of  the  iridio-chhrides  and  the  osmio-chlorid;>. 

7.  Oxy-chlorides.     This  family  embraces  a  large  number 
of  compounds,  in  which  a  metallic  oxide   is  united  with  a 
chloride,  generally  of  the  same   metal,  but  often  of  other 
metals.     These  salts  are  commonly  termed  submuriates,  on 
the  supposition  that  they  consist  of  hydrochloric  acid,  com- 
bined with  two  or  more  equivalents  of  an  oxide. 

Ory-chloridrs  of  Iron.  When  the  crystallized  protochloride  of  iron  is 
strongly  heated  in  close  vessels,  a  deep  green  osy-chloride,  in  scaly 
crystals,  is  formed.  A 

Ox ij-clil aride  of  Copper  constitutes  the  paint  called  Brunswick  preen, 
and  is  prepared  by  exposing  metallic  copper  to  hydrochloric  acid.  This 
is  the  compound  formed  by  the  action  of  sea-water  on  the  copper  of 

Vrss.'Is. 

Oxy-chtoride  of  Lead  may  be  formed  by  adding  pure  ammonia  to  a 
hot  solution  of  chloride  of  lead  ;  another  ozy-chloride  —  Hie  pigment 
called  patent  yellow  —  is  prepared  by  the  action  of  moist  sea-salt  on 
litharge. 

8.  Chlorides  with  Ammonia.     The  perchlorides  of  tin  and 
some  other  metals  absorb  ammonia  at  common  temperatures, 
and  most  of  the  other  chlorides  absorb  it  when  gently  heated  ; 
but  most  of  these  compounds  lose  their  ammonia,  on  exposure 
to  the  air,  and  nearly  all,  by  heat. 

9.  Chlorides  with  Pliosphureted  Hydrogen.      These    are 
very'similar  to  those  with  ammonia,  and  are  not  of  sufficient 
importance  to  be  inserted  in  this  place. 

10.  Double  Iodides.     These  compounds  have  not  yet  been 
closely  studied,  but  the  iodides  probably  form  with  each  other 
an  extensive  family  of  salts. 

The  most  important  are  the 

Platino-biniodide  of  Potassium,  prepared  by  digesting  an  excess  of 
biniodide  of  platinum  in  a  concentrated  solution  of  iodide  of  potassium, 
and  the  Pl&tino-biniodide  of  Hydrogen,  which  is  prepared  by  acting  on 
biniodide  of  platinum  with  a  cold  dilute  solution  of  hydriodic  acid. 

11.  Oxy-iodides.     The   best   known   of    this    family    are 
those  formed  by  the  oxide  and  iodide  of  lead. 

The  double  bromides  have  not  yet  been  studied. 


,     Organic  Chemistry.  321 

12.  Double  Fluorides.     There  are  several  extensive  fami- 
lies of  these  salts,   in  which  the  fluorides  of  boron,  silicon, 
titanium,   and  other  electro-negative  metals,  are  the  acids, 
and    the   fluorides   of  the   electro-positive    metals    are    the 
bases. 

13.  Double  Cyanurets  and  Fcrro-cyanurets.     The  double 
cyanurets  constitute   a  large  and  important  family  of  salts, 
of  which  the  principal  are  the  ferro-cyanurets,  ferro-sesqui- 
cyanurets,  zinco-cyanurets,  cobalto-cyanurets,   nicco-cyanu- 
rets,  and  cupro-cyanurets,   in  which  the  proto-cyanuret  of 
iron,   sesqui-cyanuret   of    iron,    cyanuret   of    zinc,    cobalt, 
nickel,  and  copper,  are  the  electro-negative  cyanurets.    (See 
Turner's  Elements,  p.  487.) 


CHAPTER     IV. 

NATURAL    SUBSTANCES. 
ORGANIC  CHEMISTRY. 

Organic  chemistry  treats  of  those  substances  which  are 
of  animal  or  vegetable  origin,  and  which  are  therefore  called 
organic.  These  substances  differ  from  inorganic  substances, 
in  being  composed  of  the  same  elements,  oxygen,  carbon,  and 
hydrogen,  often  with  the  addition  of  nitrogen,  which  is  most 
abundant  in  fungous  plants  and  animal  substances.  On  the 
other  hand,  inorganic  compounds  are  composed  of  very  dif- 
ferent elements;  a  few  other  constituents,  as,  iron,  silica, 
potassa,  sulphur,  phosphorus,  etc.,  are  sometimes  detected  in 
small  quantity  in  organic  substances,  but  can  rarely  be  re- 
garded as  essential  constituents.  These  compounds  differ 
chiefly  in  the  proportions  of  their  constituents ;  hence  many 
of  them  are  easily  convertible  into  each  other. 

A  second  characteristic  of  organic  substances  is  the  facility 
with  which  they  may  be  decomposed,  and  especially  in  being, 


Vegetable  Chemistry. 

without  exception,  decomposed  by  a  red^ieat,  and  often  by  a 
lower  temperature ;  if  heated  in  the  open  air,  they  are  con- 
verted chiefly  into  water  and  carbonic  acid. 

With  a  few  exceptions, organic  substances  cannot  be  formed 
artificially,  by  the  direct  union  of  their  elements ;  they  are 
obtained  only  as  already  existing  in  organic  bodies,*  or  by 
the  conversion  of  one  into  another,  as  of  sugar  into  al- 
cohol. 

Many  organic  acids  and  alkalies  combine  with  inorganic 
alkalies  or  acids,  and  form  compounds,  which,  although  not 
entirely  of  animal  or  vegetable  origin,  are  usually  described 
in  connection  with  their  organic  constituents. 

VEGETABLE   CHEMISTRY. 

Most  vegetable  substances  consist  of  hydrogen  and  carbon, 
usually  with  oxygen ;  in  fungous  plants,  and  in  some  others, 
nitrogen  is  also  present. 

Proximate  Principles.  All  compounds,  which  exist  in 
plants  ready  formed  without  artificial  processes,  as,  gum, 
sugar,  starch,  etc.,  are  called  proximate  principles ;  the  pro- 
cesses by  which  they  are  separated,  constitute  proximate. 
analysis. 

Ultimate  Analysis  consists  in  the  reduction  of  organic 
compounds  into  their  elements.  This  was  formerly  done  by 
destructive  distillation ;  the  substance  was  put  into  a  close 
vessel  and  decomposed  by  a  high  temperature ;  the  products 
were  collected  and  examined.  The  process  is  now  gener- 
ally conducted  by  means  of  the  oxide  of  copper,  which  easily 
parts  with  its  oxygen  to  the  carbon  and  hydrogen  of  the 
substance,  forming  carbonic  acid  with  the  former,  and  water 
with  the  latter.  These  new  compounds  are  collected,  and 
from  their  weight  may  be  known  the  weight  of  the  carbon 

*  The  agent  by  which  organic  bodies  are  formed  is  life,  whose  na- 
ture and  mode  of  action  we  do  not  understand. 


Vegetable  Adds.  323 

and  of  the  hydrogen.  The  loss  of  oxygen  in  the  oxide  of 
copper  is  also  noted,  and  compared  with  the  quantity  in  the 
carbonic  acid  and  water.  The  excess  of  the  latter  over  the 
former,  is  the  amount  derived  from  the  substance  under  ex- 
amination; and,  if  there  be  no  such  excess,  it  is  inferred  that 
there  was  none  in  the  substance. 

Before  entering  upon  a  description  of  the  various  vegetable 
principles,  it  will  be  proper  to  notice  the  results  of  the  late 
investigations  of  Wohler,  Liebig,  Pelouse,  and  Dumas. 

1.  Amides,  or   Amidcts. —  Theory.      Dumas   discovered 
that  when  crystallized  oxalate  of  ammonia,  represented  by 
the  formula  C'W  +  NH3  was   distilled,   a  white,    tasteless 
powder  was  obtained,  which  he  called  oxamide.     On  analyz- 
ing this,  he  found  it  composed  of  C^2  -f-  NH2 ;  or  it  is  oxalate 
of  ammonia  deprived  of  one  equivalent  or  atom  of  water. 
On  heating  this  with  potassa,  ammonia  is  disengaged,  and 
oxalate  of  potassa  formed,  by  which  treatment  the  atom  of 
water  is  restored. 

The  term  amide  has  been  generalized  and  applied  to  all 
those  anhydrous  compounds  of  an  acid  and  ammonia,  which 
by  heat  may  be  deprived  of  an  atom  of  water ;  or  to  all  those 
compounds  which,  by  adding  an  atom  of  water,  can  be  con- 
verted into  a  salt  of  ammonia ;  hence  we  have  from  bcnzoate 
of  ammonia  (C14H5O3-j-H3N)  a  substance  called  benzamide, 
(C^H^O2  -f  H2N,)  differing  from  the  former  by  HO,  or  1 
equivalent  of  water  less.  Hence  it  is  inferred  that  there  must 
be  such  a  compound  as  H2N,  to  which  Liebig  has  given  the 
name  amide,  as  potassamide,  composed  of  K  -j-  H2N. 

Dumas  has  given  to  these  compounds  the  name  of  amidet. 
Thus  oxamide  he  calls  amidet  of  oxide  of  carbon,  (H2N 
-fC2O2.) 

2.  Benzoyl.  —  Theory.     By  the  recent  investigations  of 
Wohler  and  Liebig,  on  the  volatile  oil  of  bitter  almonds,  they 
have  inferred  that  benzoic  acid  has  a  base,  to  which  they  give 
the  name  of  benzoyl,  composed  of  C14H5O2.     They  also  ob- 


324  Vegetable  Chemistry. 

tained  chloride,  bromide,  sulphuret,  and  cyanide  of  benzoyl, 
from  which  it  is  inferred  that  benzoyl  exists  as  a  separate 
compound,  and  that  it  is  capable  of  combining  with  other 
simple  bodies. 

3.  Ethers.  —  Theory.     Dumas  considers  the  base  of  ether 
to  be  C4H4.     Liebig  regards  the  base  as  thus  constituted, 
C4II5.     Sulphuric  ether,  according  to  the  latter,  is  an  oxide 
of  C4H5,  and  is  represented  by  C4H5O.     Alcohol  is  a  hy- 
drate of  sulphuric  ettier,  or  C^H)-)-  HO. 

The  radical  of  ether  (C4H5)  is  capable  of  combining  with 
chlorine,  bromine,  iodine,  and  forms  chloric,  bromic,  and 
iodic  ethers. 

4.  Pyr acids.  —  Theory.     When  several  of  the  vegetable 
acids  are  distilled,  they  undergo  decomposition,  and  new  acids 
are  generated,  which  are  called  by  the  term  pyracids.     Tar- 
taric  acid  becomes  pyrotartaric  acid ;  gallic,  pyrogallic ;  and 
so  of  several  others.    The  difference  in  composition  seem-  i<» 
be  that  a  quantity  of  water  is  expelled  by  the  heat. 

5.  Theory  of  Substitutions.      When   oxygen,   chlorine, 
bromine,  and  iodine,  unite  with  various  compounds,  the  latter 
give  out  hydrogen,  and  the  process  is  termed  dehydrogenizing. 
Thus,  when  dry  chlorine  gas  is  passed  into  pure  oil  of  bitter 
almonds,  (C^HH^-f-H,)  it  loses  its  atom  of  hydrogen,  and 
an  atom  of  chlorine  is  substituted,  and  the  compound  con- 
sists of  C^HH^-l-Cl,   a  chloride  of  benzoyl.     This  and 
other  analogous  facts  have  been  generalized  by  Dumas,  and 
the  following  general  conclusions  made  :  — 

1.  That  when  a  body  is  subjected  to  the  dehydrogenizing 
action  of  O,  Cl,  Br,  and  I,  it  gains  one  of  the  latter  for  each 
atom  it  loses  of  hydrogen. 

2.  But  if  the  body  contain  water,  it  loses  its  hydrogen 
without  any  substitution.     If,  after  this,  hydrogen  is  extracted, 
the  substitution  proceeds  as  before. 

3.  The  fundamental   radical    and   its  derivatives  will   be 
neutral  or  alkaline,  whatever  be  the  portion  of  oxygen,  hy- 
drogen, &c.,  entering  into  it.     But  when  the  oxygen,  bro- 


Vegetable  Acids.  325 

mine,  &,c.,  enter  into  combination  with  this  radical,  they 
render  it  acid.  —  T. 


SECT.    1.     VEGETABLE    ACIDS. 

Vegetable  acids  are,  for  the  most  part,  less  liable  to  spon- 
taneous decomposition  than  other  organic  substances,  al- 
though none  of  them  can  exist  at  the  temperature  of  a  red 
heat ;  they  all  contain  carbon  and  oxygen,  and  most  of  them 
hydrogen  also;  generally,  they  have  more  oxygen  than  would 
be  sufficient  to  form  water  by  combination  with  the  hydro- 
gen ;  but  a  few  have  these  elements  in  the  same  ratio  as  in 
water,  while  in  benzoic  acid  the  hydrogen  is  in  excess. 

Ojr.nlir.  Add  (C2Q3.  36,  T.  2CO  +  O.  36.24,  L.)  was  dis- 
covered by  Scheele,  in  1776,  and  is  found  in  several  plants, 
among  which  is  common  sorrel,  the  sour  taste  of  which  is 
caused  by  the  presence  of  oxalic  acid ;  it  is  obtained  also  by 
the  action  of  nitric  acid  on  sugar.  Many  other  organic  sub- 
stances, as  starch,  gum,  most  of  the  other  vegetable  acids 
also,  wool,  silk,  etc.,  are  converted  into  oxalic  acid  by  the 
action  of  nitric  acid ;  it  contains  more  oxygen  than  any  other 
organic  substance. 

Properties.  Oxalic  acid  is  sold  in  small,  slender  crystals, 
and  much  resembles  Epsom  salts,  for  which  it  is  sometimes 
mistaken  with  fatal  consequences.  But,  although  a  powerful 
poison,  it  may  be  tasted  without  danger,  when  its  strong 
acidity  will  easily  distinguish  it;  if  taken  by  accident,  pow- 
dered chalk  in  water  or  magnesia  should  be  administered. 

Oxalatcs  of  Potassa.  There  are  three  of  these  compounds, 
one  of  which,  the  binoxalate,  (HO.CW,  KO.C2O?  +  2Aq. 
155.63,)  is  often  sold  under  the  name  of  essential  salt  of 
lemons,  for  removing  the  stains  of  iron-rust  from  linen;  a  so- 
lution of  oxalic  acid  will  answer  the  same  purpose.  Quad- 
roxalate  of  potassa  is  sold  for  the  preceding,  and  is  formed 
by  dissolving  the  binoxalate  in  hydrochloric  acid,-and  crystal- 
lizing. In  this  way  the  salt  is  manufactured  on  a  large  scale. 
28 


326  Vegetable  Chemistry, 

Oxalaie  of  Lime  (CaO.CQO3  +  2Aq.  =  82.74)  exists  in 
several  species  of  lichen,  and,  when  recently  precipitated,  is 
a  snow-white  flocculent  powder.  This  salt  may  be  distin- 
guished from  most  other  precipitates  by  its  being  insoluble 
in  water,  ammonia,  and  acetic  acid,  but  soluble  in  nitric  and 
hydrochloric  acids.  On  this  account,  lime  may  be  detected 
in  solutions  from  which  all  other  metallic  oxides  have  been 
separated  :  thus  these  oxulates  are  used  to  separate  lime  from 
magnesia.  Lime  may  also  be  used  to  detect  oxalic  acid. 

Acetic  Acid.  C4H3Q3.  51.48.  This  acid  exists  in  the 
of  many  plants,  and  is  generated  in  large  quantities,  in  the 
destructive  distillation  of  vegetable  substances,  and  in  the 
acetous  fermentation  :  it  is  the  acid  of  common  vinegar. 
Distilled  vinegar  is  transparent  and  colorless,  of  a  strong 
acid  taste  and  an  agreeable  odor.  To  obtain  acetic  arid  \\\ 
a  purer  state,  saturate  distilled  Vinegar  with  a  metallic  oxide, 
as  of  copper  or  lead,  and  distil  the  compound.  Pyroligne- 
ous  acid  consists  of  acetic  acid  mixed  with  tar  and  a  volatile 
oil,  and  is  made  by  the  distillation  of  wood.  The  concen- 
trated acid  is  very  strong  and  volatile,  with  a  refreshing 
odor  ;  its  vapor  is  inflammable.  Numerous  salts  are  formed 
by  this  acid. 

Acetate  of  Lead.  1  eq.  acid,  1  protoxide  of  lead,  3  water. 
This  substance,  commonly  known  under  the  name  of  sugar 
of  lead,  is  prepared  by  dissolving  either  the  carbonate  of  lead 
(white  lead)  or  litharge  in  distilled  vinegar.  Like  most  of 
the  compounds  of  lead,  it  is  highly  poisonous.  It  is  one  of 
the  most  important  of  the  acetates.  It  is  used  in  pharmacy, 
and  by  dyers  and  calico-printers  for  the  preparation  of 
acetate  of  alumina  and  iron. 

Acetates  of  Copper.  Of  these  there  are  three  or  four. 
Verdigris  is  a  variable  mixture  of  them,  and  is  prepared  in 
France  by  covering  copper  with  the  refuse  of  grapes,  after 
the  juice  has  been  extracted.  In  England,  a  better  article  is 
prepared  by  covering  copper  plates  with  cloth  soaked  in 
pyrol igneous  acid. 


Vegetable  Acids.  327 

Acetate  of  Alumina  is  extensively  employed  by  calico- 
printers  as  a  mordant  for  fixing  colors.  Acetate  of  Iron  is 
also  used  for  the  same  purpose.  Acetate  of  Ammonia  has 
long  been  used  in  medicine.  Acetate  of  Zinc  is  sometimes 
applied  externally  as  a  remedy,  and  Acetates  of  Tin  have 
been  recommended  as  mordants  for  the  use  of  dyers.  Ace- 
tate of  Mercury  was  once  used  in  medicine. 

Malic  Acid.  C4H2O4.  60.  This  acid  is  contained  in 
grapes,  currants,  gooseberries,  oranges,  apples,  and  in  most 
of  the  acidulous  fruits.  It  is  also  obtained  by  the  action  of 
nitric  acid  on  J  of  its  weight  of  sugar ;  it  forms  salts  with 
metallic  oxides,  called  malatcs. 

Citric  Acid.  C4H2O4.  60.  This  acid  is  also  found  in 
many  acidulous  fruits,  especially  in  limes  and  lemons,  from 
which  it  is  usually  obtained.  It  has  an  agreeable  flavor,  and 
is  an  excellent  substitute  for  lemons ;  it  is  used  in  the  prep- 
aration of  lemon  sirup,  in  which,  however,  tartaric  acid  is 
largely  employed,  being  much  less  expensive,  but  of  very 
inferior  flavor.  Citric  and  malic  acids  are  isomeric. 

Tartaric  Acid.  C4H2O5.  66.24.  This  acid  also  exists  in 
acidulous  fruits,  usually  in  combination  with  lime  or  potassa. 
Tartaric  acid  is  used  with  the  bicarbonate  of  soda  for  an 
effervescing  drink  ;  it  forms  numerous  salts,  many  of  which 
are  double. 

Bitartratc  of  Potassa.  In  an  impure  form,  this  is  known 
by  the  name  of  crude  tartar,  and  is  found  incrusted  on  the 
sides  of  wine  casks,  colored  by  the  wine;  when  purified,  it  is 
white,  and  is  known  by  the  name  of  cream  of  tartar.  It  is 
used  for  the  preparation  of  tartaric  acid,  and  as  a  medicine. 

Tartrate  of  Antimony  and  Potassa.  This  compound  is 
sold  under  the  name  of  tartar  emetic,  and  is  prepared  by  boil- 
ing sesquioxide  of  antimony  with  cream  of  tartar.  It  is  neu- 
tralized by  vegetable  astringents,  as  tea,  or  Peruvian  bark, 
which  may  therefore  be  used  as  an  antidote,  in  case  of  taking 
a  too  powerful  dose.  It  is  a  white  solid,  slightly  efflores- 
cent, and  is  composed,  according  to  Phillips,  of  I  atom  of 


328  Vegetable  Chemistry. 

bitartrate  of  potassa,  3  sesquioxide  of  antimony,  and  3  of 
water. 

Tartrate  of  Potassa  and  Soda  is  prepared  by  saturating 
an  excess  of  acid  in  tartar,  with  carbonate  of  soda.  It  has 
long  been  used  in"  pharmacy  under  the  name  of  Roche  lie  Salt 
and  Sel  de  Seignctte.  It  consists  of  1  atom  of  tartrate  of 
potassa,  1  atom  of  tartrate  of  soda,  and  10  atoms  of  water.. 

Tannic  Acid,  or  Tannin.  C^HK)1*.  212.  This  substance 
exists  in  gall-nuts,  (the  excrescences  of  several  species  of  the 
oak,)  in  the  bark  of  most  trees,  in  tea,  and  in  most  vegetable 
astringents,  and  is  the  cause  of  their  astringency.  \Yith 
gelatin  or  glue,  it  forms  an  insoluble  compound,  which  is 
the  basis  of  leather.  Hence  leather  is  prepared  by  soaking 
skins  in  water,  which  contains  ground  bark,  the  tannic  acid 
of  which  is  taken  in  solution  by  the  water. 

Ezp.  To  a  strong  solution  of  gelatin  (common  glue  answers  well 
enough)  add  a  strong  infusion  of  gall-nuts;  a  white  precipitate  will  be 
formed,  and  may  be  collected  upon  a  glass  rod  and  pressed  together, 
forming  a  strong  extensible  mass,  resembling  new  leather.  When  ex- 
posed to  the  oxygen  of  the  air,  it  is  gradually  converted  into  gallic  acid. 

Gallic  Arid.  C7!!^5.  85.  This  acid  also  exists  in  gall- 
nuts  and  in  the  bark  of  trees,  but  is  more  abundantly  ob- 
tained by  the  oxidation  of  the  tannic  acid  of  gall-nuts. 
Common  ink  owes  its  color  to  the  compounds  of  tannic  -MM! 
gallic  acids  with  the  sequioxide  of  iron,  and  may  be  extem- 
poraneously prepared  by  adding  to  an  infusion  of  gall-nuts 
a  solution  of  copperas,  which  has  been  exposed  to  the  air.* 

Some  of  the  most  important  of  the  remaining  vegetable 
acids  are  the  following  :  — 

Mcllitic  Acid  (C<O3.  24.48+24  =  48.48)  is  contained  in 
the  rare  substance  called  honey-stone.  It  exists  as  a  white, 

*  A  very  good  ink  may  be  formed  thus  :  Take  8  oz.  of  bruised  galls, 
4  oz.  sulphate  of  iron,  3  oz.  gum  arabic,and  1  oz.  of  sugar  candy.  Boil 
the  galls  in  6  qts.  of  water  until  but  3  qts.  remain  ;  strain,  and  add  the 
other  ingredients,  stirring  the  whole  till  dissolved. 

Ink  may  be  kept  from  moulding  by  keeping  a  few  cloves  in  the  bot- 
tle. Common  writing  ink  is  much  more  permanent  if  Indian  ////,  — 
which  is  lampblack  made  into  a  cake  with  isinglass  —  is  dissolved  in  it, 
I  oz.  to  3  qts.  of  ink. 


Vegetable  Acids.  329 

slightly-crystalline  powder,  soluble  in  alcohol;  and,  by  boil- 
ing the  solution,  there  seems  to  be  formed  an  acid  —  mellitate 
of  ether.  It  forms  salts  called  mellitates. 

Croconic  Acid  (C5O4.  30.6  +  32  =  62.6)  -is  a  yellow,  ea- 
sily-crystallized solid,  soluble  in  water  and  in  alcohol.  All 
its  suits  are'  yellow. 

Lactic  Acid,  (CeHPO5.  36.72  +  5  +  40  =  81.72,)  so 
called  from  being  first  noticed  in  sour  milk,  was  discovered  by 
Scheele,  in  1780.  It  has  since  been  found  in  several  vegeta- 
ble bodies  when  left  to  spontaneous  fermentation.  It  is  col- 
orless, without  smell,  but  excessively  sour.  Its  salts  are 
termed  lactates. 

Kinic  Acid  (C15H10OK>.  91.8  +  10  +  80  =  181.8)  exists 
in  cinchona  bark,  in  combination  with  lime,  quinia,  and 
cinchonia. 

Vyrocitric  Acid.    C10H2O3.  61.2  +  2  +  24  =  87.2. 

Racemic  Acid  (C4H2O5.  24.48  +  2  +  40  =  66.48)  is  as- 
sociated with  tartaric  acid  in  the  juice  of  the  grape. 

Benzine  Acid  (C14H5Q3.  85.68  +  5  +  24=114.68)  ex- 
ists in  gum  benzoin,  from  which  it  is  commonly  extracted,  in 
the  balsams  of  Peru,  and  in  several  other  vegetable  sub- 
stances, in  the  urine  of  the  cow  and  other  herbaceous  ani- 
mals. This  acid  crystallizes  in  soft,  white  scales,  flexible, 
transparent,  and  of  a  pearly  lustre  ;  or  in  hexagonal  needles ; 
is  slightly  biting,  but  of  a  sweetish  taste,  producing  sensation 
in  the  throat ;  fuses  at  250°,  and  sublimes  at  300°. 

Exp.  Suspend  a  small  branch  of  a  shrub  in  a  tall  glass,  without  a 
bottom ;  place  a  small  quantity  of  the  acid  upon  a  plate  of  metal ; 
place  the  jar  over  the  plate,  at  the  same  time  applying  the  heat  of  a 
lamp  to  evaporate  the  acid  ;  the  branch  will  be  covered  with  delicate 

white  crystals. 

Meconic  Acid  (C7H3O7.  42.84  +  2  +  56=100.84)  is 
found  in  the  poppy,  in  combination  with  morphia,  and  crys- 
tallizes in  white,  transparent  scales. 

Pyromeconic  Acid.     C10H;3O4. 

Metameconic  Acid  (C12H4O10.  73.44  +  4  +  80  =  157.44) 
is  obtained  from  the  meconic  by  boiling  its  aqueous  solution. 
28* 


330  Vegetable  Chemistry. 


Pyrogallic  Acid  (CSHW  36.72  +  3  +  24  =  63.72)  is 
obtained  by  heating  galJic  acid  to  419°. 

Metagallic  Add  (C^HW  73.44  +  3  +  24  —  100.44)  is 
formed  by  beating  gallic  acid  to  480°. 

Ellagic  Acid  (C7R2CH.  42.84+2  +  32=76.84)  is  very 
similar  to  the  preceding. 

SuccinicAcid  (C4H2O3.  24.48  +2  +  24  =50.48)  exists 
in  amber,  and  is  obtained  by  the  aid  of  heat.  It  is  obtained 
in  three  states  :  —  1.  Combined  with  an  atom  of  water,  which, 
when  pure,  is  the  crystallized  acid  of  the  shops.  2.  With  J 
an  atom  of  water,  produced  by  keeping  the  crystallized  acid 
for  a  long  time  between  the  temperatures  of  260°  and  284°. 
3.  Anhydrous.  The  compounds  which  this  acid  forms  \\itli 
bases  are  termed  succinates. 

Mncic  Acid.   C6H5Q8.  36.72  +  5  +  64  =  105.72. 

Camphoric  Acid  (&*>H™O*.  122.4  +  10+  40—  178.4) 
is  obtained  from  camphor  by  nitric  acid. 

Vakrianic  Acid  (C10H^O3.  61.2  +  9  +  24  =  94.2)  ex- 
ists in  the  root  valerian,  and  is  obtained  by  distillation. 

Rocellic  Acid.  C^H^O4.  97.92  +  16  +  32  =  1  45.1>2. 

Moroxylic  Acid  is  found,  in  combination  with  lime,  on  the 
bark  of  the  white  mulberry. 

Oily  Acids,  so  called  because  they  are  obtained  from  oils 
or  fat,  and  enter  into  the  composition  of  soaps. 

Stearic  Acid  (C™H6O5.  527)  is  obtained  from  soap,  and 
is  a  white,  tasteless,  inodorous  substance,  insoluble  in  water, 
and  burning  like  wax.  Its  salts  are  termed  stearates. 

Margaric  Acid  (C70H70O9.  562)  is  distinguished  from  the 
preceding  by  fusing  at  140°.  When  distilled  with  lime,  a 
white  substance  is  obtained,  called  margarone. 

Okie  Acid  (C70H62O7.  538)  is  obtained  from  the  soap 
made  from  linseed  oil  and  potassa.  It  burns  like  the  fixed 
oils,  and  forms  salts,  or  soaps,  called  olcates.  When  olive  oil 
is  mixed  with  half  its  weight  of  concentrated  sulphuric  acid, 
three  acids  are  formed,  one  of  which  has  been  called  sulpho- 
okic  ;  and  this,  when  decomposed,  affords  hydro-olcic  acid. 


Vegetable  Acids.  331 

From  this  last  compound  two  liquids  have  been  obtained,  of 
the  same  composition  with  olefiant  gas.  The  one  has  been 
called  olein,  the  other  elain. 

Olcin  (C6H6)  is  a  white  liquid,  lighter  than  water,  strong 
odor,  very  combustible,  burning  with  a  greenish  flame,  and 
yielding  a  poisonous  vapor. 

Elain  is  composed  of  C9  -|-  H9,  and  burns  with  a  fine  white 
flame. 

The  Azulmic  Add,  (C8H4N4O4,)  the  Indigotic,  (C^HTJ 
N1£O15,)  which  is  obtained  by  boiling  indigo  in  rather  dilute 
nitric  acid,  and  the  Carbazotic  acids,  (C15N3O15.  252,)  also, 
are  obtained  from  indigo  containing  nitrogen. 

Pcctic  Acid  (CnH7O10.  153)  has  been  imperfectly  ex- 
amined. 

Crenic  Acid  (108)  was  discovered  by  Berzelius,  in  1832, 
in  the  water  of  Porla  well,  in  Sweden.  It  is  inodorous,  a 
sharp,  followed  by  an  astringent  taste,  yellow  and  trans- 
parent; very  soluble  in  water  arid  in  alcohol.  When  the 
solution  is  exposed  to  the  air,  apocrenic  acid  is  formed. 
Its  salts  are  termed  crenates,  and  resemble  extracts  in  ap- 
pearance, but  are  incapable  of  crystallizing. 

Apocrenic  Acid  (132)  was  obtained  by  digesting  the  ochre 
of  Porla  well  with  potassa,  and  precipitating  the  acid  by 
means  of  acetate  of  copper.  The  apocrenate  of  copper  falls, 
from  which  the  acid  is  separated  by  the  action  of  hydrosui- 
phunc  acid,  absolute  alcohol,  and  potassa.  It  is  a  brown 
substance,  resembling  a  vegetable  extract.  Crenic  and  apo- 
crenic acids  have  been  detected  in  many  waters,  and  in  the 
vegetable  mould  of  soils. 

There  are  also  a  numerous  class  of  compound  acids.  For 
a  complete  description  of  the  vegetable  acids,  the  student  is 
referred  to  Thompson's  Chem.,  Organ.  Bodies. 

Cyanogen  and  its  Compounds.  A  numerous  class  of 
bodies  are  formed  by  the  combination  of  cyanogen  with  other 
substances  which  exist  in  the  vegetable  and  mineral  king- 
doms;  for  a  description  of  which,  see  Webster's  Chem.,  and 
also  Thompson's  Chem.,  Organ.  Bodies. 


332  Vegetable  Chemistry. 

SECT.  2.     VEGETABLE  ALKALIES. 

The  existence  of  vegetable  alkalies  was  not  known  until 
the  present  century,  and  very  little  attention  was  given  to 
them  until  1816.  They  are  eighteen  or  twenty  in  number. 
Their  constitution  is  remarkable,  as  they  each  contain  1 
equiv.  of  nitrogen  in  eaqh  equiv.  of  the  alkali.  The  equiva- 
lents of  oxygen  vary  from  one  to  six,  of  hydrogen  from 
twelve  to  twenty-two,  and  of  carbon  from  twenty  to  thirty- 
four  ;  all,  which  have  been  analyzed,  consists  of  these  four 
elements.  In  vegetable  bodies  they  usually  exist  in  combi- 
nation with  acids,  forming  salts. 

The  method  of  preparation  is  nearly  the  same  for  all  of 
these  alkalies;  the  substance  which  contains  one  of  them  is 
steeped  in  a  large  quantity  of  water,  which  dissolves  the  salt 
that  contains  it;  the  solution  is  boiled  for  a  short  time  with 
lime  or  magnesia,  and  the  vegetable  alkali  is  set  free  in  ;m 
insoluble  state,  and  may  be  collected  on  a  filter  with  the  Inm  ; 
if  then  boiled  in  alcohol  with  powdered  charcoal,  it  is  dis- 
solved by  the  former,  and  purified  by  the  latter ;  then,  by 
filtering  while  hot,  it  is  separated  from  the  charcoal,  and  the 
lime  with  which  it  was  mixed;  it  is  deposited  from  the  alco- 
hol on  cooling,  by  evaporation. 

Morphia.  C34H18N1O6  =  284.  This  alkali  is  the  narcotic 
principle  of  opium,  in  which  it  is  combined  with  sulphuric 
and  meconic  acids,  and  is  associated  with  several  other  vege- 
table alkalies,  and  with  gummy,  resinous,  and  coloring  mat- 
ters. Opium  contains  about  nine  and  a  half  per  cent,  of  mor- 
phia ;  when  pure,  it  is  very  insoluble  in  water,  and  conse- 
quently but  little  poisonous ;  but  when  in  the  state  of  a  salt, 
as  in  opium,  it  is  a  very  powerful  poison ;  one  half  a  grain  in 
solution  will  produce  alarming  effects  on  the  animal  system. 
When  opium  has  been  administered  as  a  poison,  the  presence 
of  its  morphia  may  be  detected  by  a  process  too  elaborate  to 
be  inserted  here.  A  skilful  chemist  will  detect  a  single  grain 
of  morphia  in  700  grains  of  water.  Some  of  the  salts  of  mor- 


Vegetable  Alkalies.  333 

phia  are  useful  as  medicines;  of  which  ihe-Jiydrochlorate  and 
acetate  are  the  principal. 

Narcotina(C40R^NO^  =  370.24)  was  discovered  by  Des- 
rone,  in  1803,  and  is  obtained  from  opium  ;  it  is  a  white  sub- 
stance, and  may  be  taken  into  the  human  stomach  without 
sensible  effects,  but  it  is  speedily  fatal  to  dogs. 

Cinchonia  (C20H12NO1J=  153)  and  Quinia,  (C2<>Hi2NO2 
—  162.)  These  two  alkalies  were  detected  by  Pelletier  and 
Caventou,  in  1820,  in  Peruvian  bark,  and  impart  to  it  its 
value  as  a  medicine.  Cinchonia  is  found  in  the  pale  bark  ; 
quinia,  with  a  little  cinchonia,  in  the  yellow  bark  ;  and  both  in 
the  red  bark.  Cinchonia  is  insoluble  in  cold  water,  and 
nearly  so  in  hot  water ;  in  boiling  alcohol  it  is  freely  dissolved, 
and  the  solution  has  an  intensely  bitter  taste ;  some  of  its  salts 
are  soluble  in  water. 

Quinia,  or  Quinine,  is  also  almost  insoluble  in  water,  but 
with  alcohol  forms  an  intensely  bitter  solution. 

Quinia  forms  several  salts,  one  of  which,  the  sulphate,  is 
manufactured  in  large  quantity  for  medical  purposes,  and  is 
commonly  sold  by  the  name  of  quinine.  It  is  soluble  in  al- 
cohol, or  slightly  in  pure  water,  and  freely  if  the  water  is 
slightly  acidulated  by  sulphuric  acid;  the  solution,  although 
containing  but  a  minute  portion  of  quinia,  is  intensely  bitter. 

On  account  of  its  high  value,  sulphate  of  quinia  is  often 
adulterated  with  gum,  starch,  sugar,  magnesia,  and  various 
other  substances ;  gum  and  starch  are  insoluble  in  alcohol, 
and  may  be  detected  by  dissolving  the  suspected  quinia  in 
boiling  alcohol.  Sugar  may  be  detected  by  adding  pearlash 
to  the  solution  in  water,  when  the  quinia  will  be  thrown 
down,  and  the  sweet" taste  may  be  perceived;  magnesia  will 
be  left  after  burning  a  portion  of  the  adulterated  article. 

Strychnia  (C^H^NO3  —  237.75)  was  discovered  in  1818, 
by  Pelletier  and  Caventou.  This  remarkable  alkali  is  found  in 
the  nux  vomica  and  in  the  upas-tree.  It  is  freely  soluble  in 
alcohol,  nnd  but  slightly  so  in  water ;  although  nearly  insoluble 
in  the  latter,  the  minute  portion  which  is  taken  up,  commu- 
nicates to  the  water  the  most  intense  bitterness;  a  single 


334  Vegetable  Chemistry. 

grain  of  strychnia  will  render  eight  gallons  of  water  bitter. 
It  is  one  of  the  most  virulent  poisons  yet  discovered  ;  half  a 
grain  in  the  throat  of  a  rabbit  occasioned  death  in  five 
minutes.  Its  action  is  always  accompanied  by  symptoms  of 
locked-jaw. 

Emetia.  This  alkali  constitutes  16  per  cent,  of  ipeciim- 
anha,  and  appears  to  be  the  sole  cause  of  its  emetic  proper- 
ties. 

Sanguinaria  is  a  peculiar  alkali,  discovered,  by  Mr.  Dana, 
in  the  blood  root,  (sanguinaria  Canadensis.)  Its  salts  have  a 
red  color. 

Nicotina  is  the  peculiar  principle  of  tobacco ;  it  is  a  viru- 
lent poison. 

Codeia;  discovered  in  1832,  by  Robiquet,  in  the  hydrochlo- 
rate  of  morphia.  When  taken  into  the  stomach  in  doses  of 
from  4  to  6  grains,  it  produces  an  excitement  similar  to  in- 
toxication, followed  by  depression,  nausea,  and  vomiting. 

jBrt/cia,  or  Brucina,  resembles  strychnia,  and  may  be  pro- 
cured from  the  nuz  vomica.  It  is  intensely  bitter,  less  poison- 
ous than  strychnia,  but  similar  in  its  effects. 

Conia  is  the  active  principle  of  conium-maculatum ,  or  hem- 
lock, and  is  the  most  virulent  poison  known,  with  the  excep- 
tion of  hydrocyanic  acid. 

Parillia,  or  Parillina,  exists  in  the  common  sarsaparilla  of 
commerce.  Its  color  is  white,  taste,  sharp  and  bitter,  and, 
when  swallowed  to  the  extent  of  13  grains,  produces  nausea, 
vomiting,  diminishes  the  rapidity  of  the  circulation,  and  acts 
as  a  sudorific. 

SECT.  3.     NEUTRAL  SUBSTANCES. 

Sugar.  C12H10O10  =  162.24.  Sugar  is  found  in  most  ripe 
fruits,  but  more  abundantly  in  the  sap  of  the  maple-tree,  in 
the  sugar-beet,  and  in  the  sugar-cane  ;  from  the  latter  it  is 
obtained  by  evaporating  the  juice  by  a  moderate  ebullition, 
until  the  sirup  is  sufficiently  thick  to  crystallize  on  cooling. 
During  this  operation,  lime  water  is  added  to  neutralize  the 


Neutral  Substances.  335 

acid  present,  and  to  remove  impurities  which  rise  with  the 
lime  in  a  scum  to  the  surface;  it  is  next  drawn  off  into  shal- 
low coolers,  in  which  it  becomes  a  soft  solid.  Lastly,  it  is 
put  into  barrels  with  holes  in  the  bottom,  through  which  the 
molasses  gradually  runs  out,  leaving  raw  or  brown  sugar. 
Raw  sugar  is  purified  by  boiling  it  with  the  white  of  eggs  or 
bullock's  blood  and  lime  water ;  it  is  then  received  into  con- 
ical vessels,  and  in  cooling  assumes  the  form  of  loaf  sugar. 

When  two  pieces  of  loaf  sugar  are  rubbed  together  in  the 
dark,  phosphorescence  is  observed  ;  it  is  obtained  in  large 
crystals  by  fixing  threads  in  a  sirup,  which  evaporates  grad- 
ually in  a  warm  room ;  in  this  state  it  is  called  rock-candy. 
Sugar  does  not  deliquesce  when  exposed  to  the  air,  except 
when  impure,  as  raw  sugar.  It  is  soluble  in  an  equal  weight 
of  cold  water,  and  is  much  more  soluble  in  warm  water ;  it  is 
soluble  in  four  times  its  weight  of  boiling  alcohol,  from 
which  solution  fine  crystals  are  obtained.  The  vegetable 
acids  diminish  the  tendency  of  sugar  to  crystallize,  as  in 
molasses. 

By  the  action  of  sulphuric  acid,  starch,  and  common 
wood,  may  be  converted  into  sugar. 

Sugar  of  Grapes  (C12H12O12)  contains  rather  less  carbon 
than  common  sugar,,  and  is  rather  less  sweet. 

Honnj  consists  of  two  kinds  of  sugar,  one  of  which,  when 
separated,  crystallizes,  and  the  other  is  uncrystallizable.  Be- 
sides sugar,  it  contains  gum,  and  probably  an  acid  ;  when  di- 
luted with  water,  honey  undergoes  the  vinous  fermentation. 
Common  sugar  requires  the  addition  of  yeast  for  this  change. 

Manna  is  the  concrete  juice  of  several  species  of  ash,  and 
owes  its  sweetness,  not  to  sugar,  but  to  a  distinct  principle 
called  mannite. 

Liquorice  owes  its  sweetness  to  a  saccharine  principle 
which  is  quite  distinct  from  sugar. 

Starch.  Starch  exists  abundantly  in  the  vegetable  king- 
dom. It  is  the  principal  constituent  of  most  kinds  of  grain, 
potatoes,  and  other  farinaceous  substances.  It  is  obtained 


336  Vegetable  Chemistry. 

from  potatoes  by  washing  them  in  cold  water,  when  the  glu- 
ten, which  is  the  other  principal  constituent,  remains  in  the 
hand,  and  the  starch  is  mechanically  diffused  through  the 
water.  The  water  is  then  allowed  to  stand,  and  the  starch 
subsides,  while  the  saccharine  and  mucilaginous  matters 
remain  in  solution.  When  made  from  the  dough  of  wheat 
flour,  the  water  containing  the  soluble  and  insoluble  parts  of 
the  flour  is  allowed  to  ferment ;  acetic  acid  is  thus  formed, 
which  dissolves  the  gluten,  and  facilitates  the  separation  of 
the  starch. 

Starch  is  easily  converted  into  sugar.  In  the  germination 
of  seeds,  and  in  the  malting  of  barley  or  other  grain,  this 
change  takes  place.  If  starch  is  boiled  for  a  considerable 
time  in  water,  which  contains  -fa  its  weight  of  sulphuric  acid, 
it  is  converted  into  a  kind  of  sugar  like  that  obtained  from 
grapes. 

Arrow-root,  prepared  from  the  root  of  a  plant,  is  a  very 
pure  starch.  Sago,  prepared  from  the  pith  of  an  East  India 
palm-tree,  and  tapioca  and  cassava  from  the  root  of  a  plant, 
are  essentially  the  same. 

Gluten.  Gluten  exists  with  starch  in  most  kinds  of  grain, 
which  are  chiefly  composed  of  two  principles.  It  is  obtained 
from  wheat  flour  by  washing  out  the  starch  and  soluble  mat- 
ter, and  boiling  the  remainder  in  alcohol.  On  adding  water 
and  distilling  off  the  spirit,  it  is  deposited.  It  is  without 
taste,  very  tenacious,  elastic,  and  insoluble  in  water.  When 
kept  warm  and  moist,  it  ferments.  The  tenacity  of  common 
paste  is  owing  to  the  gluten  which  it  contains.  The  rising 
of  bread  is  caused  by  the  fermentation  of  gluten,  the  tenacity 
of  which  retains  the  bubbles  of  carbonic  acid  gas  formed  in 
fermentation.  Gluten  has  been  resolved  into  four  distinct 
principles,  viz.,  vegetable  albumen,  emulsin,  mucin,  and 
glutin.  These  substances  are  obtained  by  the  action  of 
alcohol  upon  the  gluten  of  wheat. 

Gum.  Under  this  name  are  included  all  those  vegetable 
principles  which  form,  when  dissolved  in  water,  an  adhesive, 


Oils.  337 

viscid  liquid,  called  mucilage,  and  which  yield  an  acid,  called 
mucic  acid,  when  boiled  with  four  times  their  weight  of 
nitric  acid.  Gum  is  insoluble  in  ether  and  alcohol,  and  is 
precipitated  by  them  from  its  aqueous  solution,  as  an  opaque, 
white  substance;  but,  with  acids  and  alkalies,  it  is  more 
soluble  than  in  pure  water. 

Gum  Arabic  is  the  most  common  variety  of  gum ;  it  is 
obtained  from  several  species  of  acacia  or  mimosa  in 
Africa  and  Arabia.  Gum  Senegal  differs  in  no  important 
respect  from  gum  arabic.  The  gum  of  the  peach,  plum, 
and  cherry-tree,  although  identical  in  composition  with  gum 
arabic,  differs  in  being  insoluble  in  cold  water;  after  being 
boiled,  however,  it  assumes  the  characters  of  that  gum. 
Gum  Tragacanth  differs  from  gum  arabic  in  containing  a 
large  portion  of  bassoric,  starch,  and  water;  it  is  tougher 
than  common  gum,  which  is  quite  brittle.  Gum  tragacanth 
is  therefore  a  very  useful  ingredient  in  paste.  The  jelly  of 
fruits  is  distinct  from  gum  in  some  properties,  but  is  nearly 
allied. 

Lignin.  Lignin,  or  the  woody  fibre,  constitutes  the 
fibrous  structure  of  plants,  and  is  the  most  abundant  prin- 
ciple in  them.  The  common  kinds  of  wood  contain  about 
96  per  cent,  of  lignin.  It  is  insoluble  in  alcohol  or  water. 
With  strong  alkalies  or  acids,  it  is  changed.  With  sulphuric 
acid,  it  is  changed  into  gum,  and,  on  boiling,  is  further 
changed  into  a  sugar  like  sugar  of  grapes.  Straw,  bark, 
and  linen,  in  the  same  way,  may  be  converted  into  sugar. 

SECT.  4.     OILS. 

These  substances  are  divided  into  fixed  and  volatile  oils. 
The  former  are  not  much  affected  by  a  heat  which  does  not 
decompose  them,  while  the  latter  rapidly  pass  away  in  vapor. 
The  greasy  stain  of  the  former  on  paper,  or  any  other  sur- 
face, is  permanent ;  that  of  the  latter  soon  disappears. 

1.  Fixed  Oils.  The  vegetable  fixed  oils  are  usually  ob- 
29 


338  Vegetable  Chemistry. 

tained  from  seeds;  as  the  almond,  linseed,  and  poppy-seed. 
Olive  oil,  however,  is  extracted  from  the  pulp  around  the 
stone.  The  density  of  these  oils  is  less  than  water,  varying 
from  .9  to  .96.  They  are  solid  at  a  low  temperature.  They 
burn  with  a  clear,  white  light.  By  exposure  to  the  air,  they 
become  rancid,  and  at  length  viscid.  In  this  change,  oxygen 
is  absorbed  ;  and  the  oil  itself  probably  undergoes  some 
change,  although  it  has  been  supposed  that  rancidity  was 
caused  by  the  acidification  of  some  mucilage  present.  By 
heating  the  oil  in  open  vessels,  it  acquires  the  property  of 
drying  rapidly ;  in  which  process  much  oxygen  is  absorbed, 
and  carbonic  acid  and  hydrogen  given  off.  Drying  oils  are 
used  for  paint,  and,  when  mixed  with  lampblack,  constitute 
printers'  ink.  Drying  oils  sometimes  absorb  oxygen  so 
rapidly  as  to  set  fire  to  combustibles.  Spontaneous  com- 
bustion often  occurs  where  cotton  has  been  moistened  with 
them. 

By  means  of  mucilage  or  sugar,  the  fixed  oils  may  be 
permanently  suspended  in  water.  Such  a  mixture  is  called 
an  emulsion.  With  ammonia,  they  form  a  soapy  liquid  called 
volatile  lini?nent,  which  is  a  direct  compound  of  oil  and  the 
alkali.  The  fixed  alkalies  have  a  similar  action  in  the  cold, 
but,  when  heated,  soap  is  generated.  A  further  notice  of 
soaps  will  be  found  under  Animal  Chemistry. 

The  fixed  oils  consist  of  two  proximate  principles,  one  of 
which,  called  margarine,  is  solid  at  common  temperatures, 
while  the  other  is  fluid,  and  is  called  oleine.* 

These  oils  consist  of  carbon,  hydrogen,  and  oxygen. 

The  principal  fixed  oils  are  the  following :  — 

Olive  Oil,  which  is  expressed  from  the  pericarpum  of  the 
fruit  of  the  common  olive,  (olea  Europea.)  By  the  action 
of  hyponitrous  acid,  the  solid  substance  called  elaidin  is 
formed.  It  contains  an  acid  called  claidic,  which  combines 
with  alkalies  and  forms  soaps.  It  is  used  as  an  article  of 
luxury. 

*  From  tiaiov,  oil. 


Oils.  339 

Croton  Oil  is  obtained  from  the  croton  tiglium  of  the 
East  Indies,  and  possesses  powerful  purgative  properties. 

Palm  Oil  has  the  consistency  of  lard,  and  is  used  in  the 
manufacture  of  yellow  soap. 

Cocoa-nut  Oil  is  a  white,  hard  substance,  used  as  a  sub- 
stitute for  tallow.* 

2.  Volatile  or  Essential  Oils.  The  flavor  of  aromatic 
plants  is  owing  to  the  presence  of  volatile  oils,  which  are 
obtained  by  distillation.  Water  must  be  added  to  the  plants 
to  keep  them  from  burning.  Some,  however,  are  obtained 
by  expressing  the  rinds  of  certain  fruits,  such  as  the  orange, 
lemon,  bergamot.  Although  usually  of  an  agreeable  odor, 
those  oils  have  an  unpleasant,  acrid  taste ;  but,  when  diluted, 
some  of  them  have  an  agreeable  taste.  They  are  but  slight- 
ly soluble  in  water,  and  are  freely  dissolved  in  alcohol. 
Such  solutions  are  commonly  sold  under  the  name  of 
essences.  Like  the  fixed  oils,  they  burn  with  a  clear,  white 
light.  They  have  the  property  of  dissolving  sulphur,  and 
the  solution  is  called  balsam  of  sulphur. 

A  few  of  these  oils  —  as  the  oil  of  turpentine,  of  lemons, 
and  of  copaiva  —  contain  only  carbon  and  hydrogen ;  others 
contain  oxygen  also.  A  few  contain  one  or  more  additional 
elements,  as  sulphur  and  nitrogen. 

The  principal  volatile  oils  are,  oil  of  turpentine,  lemons,  anise, 
juniper,  camomile,  caraway,  lavender,  peppermint,  rosemary,  cam- 
phor, cinnamon,  cloves,  sassafras,  mustard,  and  bitter  almonds. 

Common  Spirits  of  Turpentine  consists  of  resin  dissolved 
in  the  oil  of  turpentine  —  which  last  may  be  obtained  by 
distillation. 

Camphor  is  a  volatile  oil,  solid  at  common  temperatures. 
On  account  of  its  toughness,  it  is  pulverized  with  difficulty, 
unless  a  few  drops  of  alcohol  be  added.  It  is  insoluble  in 
water,  but  is  freely  soluble  in  alcohol.  Artificial  camphor 


*  The  various  kinds  of  wax  —  such  as  beeswax,  myrtle  wax,  and 
cow-tree  wax  —  are  regarded  as  similar  in  composition  with  the  fixed 
oils,  and  are  classed  by  some  chemists  with  them. 


340  Vegetable  Chemistry. 

may  be  formed  bypassing  a  current  of  hydrochloric  acid  gas 
through  oil  of  turpentine  or  oil  of  lemons.  Camphor  is  very 
offensive  to  insects,  which  are  prevented  from  devouring  cab- 
inets of  natural  history,  collections  of  birds,  insects,  etc.,  by 
placing  pieces  of  camphor  in  the  cases. 

Resins.  Resins  are  the  concrete  juices  of  plants,  solid, 
brittle,  and  without  taste;  they  are  good  non-conductors 
of  electricity,  and,  by  friction,  become  negatively  electrified; 
they  are  easily  melted,  and  burn  with  a  yellow  flame  and 
dense  smoke.  They  are  soluble  in  alcohol,  ether,  and  the 
essential  oils,  but  are  quite  insoluble  in  water. 

The  different  kinds  of  resin  are  numerous. 

Common  Resin  is  procured  by  heating  turpentine;  the 
volatile  oil  is  expelled,  and  resin  remains. 

Turpentine  is  the  juice  of  several  species  of  pine-trees. 
Other  resins  are  copal,  lac,  mastic,  and  dragon's  blood. 

Copal  is  the  most  important,  and  is  used  for  varnish.  In- 
dian ink  is  a  solution  of  borax,  lac,  and  lampblack. 

The  uses  of  resin  are  various.  Dissolved  in  oil  or  alco- 
hol, and  diluted  with  spirits  of  turpentine,  they  form  various 
kinds  of  varnish.  Sealing-wax  is  made  of  lac,  turpentine, 
and  common  resin.  It  is  colored  red  with  cinnabar  or  red 
lead,  or  black  with  lampblack. 

The  soot,  which  is  procured  from  the  combustion  of  res- 
inous wood,  turpentine,  or  resin,  is  lampblack.  When  tur- 
pentine is  extracted  by  heat,  it  is  partially  changed,  and  be- 
comes tar.  When  tar  is  thickened  by  boiling,  it  becomes 
pitch. 

Amber  is  a  fossil  substance,  consisting  of  a  peculiar  bitumi- 
nous matter  and  resin  ;  it  often  contains  insects. 

Balsams  are  the  juices  of  some  kinds  of  trees.  Some  are 
solid,  others  are  liquid:  They  are  composed  of  resin  and 
benzoic  acid. 

Gum  Resins  are  the  hardened  juices  of  certain  plants,  con- 
sisting of  resin,  gum,  and  volatile  oil.  Their  proper  solvent, 
therefore,  is  a  mixture  of  alcohol  and  water,  or  common 


Oils.  —  Alcohol  341 

spirits.  They  are  numerous,  and  many  of  them  are  valuable 
medicines;  among  them  are  aloes,  asafoRtida,  galbanum, 
gamboge,  myrrh,  and  guaiacum. 

Caoutchouc^  or  India  rubber,  is  obtained  from  four  species 
of  trees,  two  of  which  grow  in  South  America,  and  two  in 
the  East  Indies.  It  is  usually  black,  but  when  not  darkened 
by  smoke,  is  of  a  whitish  color.  It  burns  with  a  bright  flame ; 
is  insoluble  in  water  or  alcohol.  It  is  soluble  in  ether,  the 
essential  oils,  etc.  If  a  bag  of  it  be  soaked  in  ether,  it  will 
become  soft  and  gelatinous  before  dissolving,  and  in  that 
state  may  be  blown  out  into  a  very  large  and  thin  bag.  The 
most  useful  solvent  of  caoutchouc  is  a  dark,  volatile  liquid, 
obtained  by  the  careful  distillation  of  caoutchouc  itself; 
about  four  fifths  of  the  solid  pass  over  in  this  liquid  form. 

Wax.  Wax  is  found  in  the  pollen  or  dust  of  flowers,  on 
some  leaves  as  a  kind  of  varnish,  and  especially  on  the  berries 
of  the  wax-plant,  (myrica  cerifera.)  As  bees  deposit  wax, 
when  fed  only  on  sugar,  beeswax  is  an  animal  product.  Wax 
is  insoluble  in  water,  and  is  sparingly  dissolved  by  alcohol 
and  ether.  It  is  composed  of  two  principles,  cerin  and 
myricin. 

Creosote.  This  substance  exists  in  tar,  and  in  pyroligne- 
ous  acid.  It  is  a  colorless,  oily  liquid,  with  an  odor  like 
smoked  meat.  It  has  a  burning  taste,  followed  by  sweetness. 
Its  most  remarkable  property  is  that  of  preserving  meat.  The 
antiseptic  properties  of  smoke,  and  crude  pyroligneous  acid, 
appear  to  be  owing  to  this  substance.  It  is  soluble  in  80 
parts  of  water,  and  freely  in  alcohol.  Insects  and  fish  are 
killed  by  the  aqueous  solution.  It  is  said  to  be  useml  as  a 
cure  for  toothache,  ulcers,  etc. 

SECT.  5.     SPIRITUOUS  AND  ETHEREAL  SUBSTANCES. 

Alcohol.     C4H5O  +  HO.  46.    This  substance  is  the  prod- 
uct only  of  fermentation,  and  is  never  found  ready  formed  in 
any  vegetable  substance.     It  is  obtained  by  the  distillation 
of  ardent  spirits,  of  which  it  constitutes  50  per  cent.     After 
29* 


342  Vegetable  Chemistry. 

a  second  distillation,  it  still  contains  some  water,  most  of 
which  may  be  removed  by  carbonate  of  potassa  added  in  a 
dry  state.  Common  alcohol  has  a  specific  gravity  of  about 
.86,  but  when  freed  from  water,  of  .82.  The  purest  alcohol 
boils  at  a  temperature  of  170°  Fahr.,  is  highly  inflammable, 
burning  with  a  very  pale  blue,  but  hot  flame.  No  smoke  is 
produced  in  its  combustion,  and  hence  it  is  of  great  utility 
for  lamps  in  a  laboratory,  various  kinds  of  apparatus  being 
thus  conveniently  heated,  and  not  soiled  with  smoke.  Al- 
though exposed  to  a  temperature  of  -176°  Fahr.,  pure  alco- 
hol has  never  been  frozen. 

Alcohol  combines  with  water  in  every  proportion ;  with 
an  tqual  quantity  of  water,  it  constitutes  spirit  of  the  Jirtt 
proof.  The  density  of  this  is  about  .92.  The  density  will 
be  in  proportion  to  the  weakness  of  the  spirit.  Proof  spirit 
is  very  useful,  in  cabinets  of  natural  history,  for  the  preser- 
vation of  specimens  of  fishes,  reptiles,  etc.  Its  effects  upon 
the  animal  system,  as  a  poison,  are  well  known :  it  has  the 
power  of  passing  into  the  circulation  undigested,  and  ir- 
ritates all  the  organs  with  which  it  comes  in  contact.  The 
stronger  wines  contain  18  to  25  per  cent.,  and  the  weaker 
from  12  to  17  per  cent.  In  wines  it  appears  to  have  less  in- 
toxicating power  than  in  ardent  spirits,  which  may  be  owing 
to  its  chemical  combination  with  mucilaginous  and  saccha- 
rine matters. 

As  a  solvent,  alcohol  is  useful.  Many  vegetable  princi- 
ples, not  soluble  in  water,  are  freely  so  in  alcohol.  Both 
mineral  and  vegetable  alkalies  are  soluble,  but  it  does  not 
dissolve  the  earths,  or  other  metallic  oxides. 

Ethers.  Most  of  the  stronger  acids,  when  heated  with 
alcohol,  yield  a  very  volatile,  inflammable  liquid,  called  ether. 
Different  kinds  are  formed  from  different  acids. 

Sulphuric  Ether  (C4!!^))  is  the  most  common.  It  is  pre- 
pared by  boiling  equal  weights  of  alcohol  and  sulphuric  acid  ; 
the  vapor  of  ether  passes  over,  and  is  condensed  in'  a  vessel 
surrounded  by  ice-cold  water. 


Ether.  —  Coloring  Matters.  343 

The  specific  gravity  of  pure  ether  is  .7;  as  commonly  sold, 
.74.  It  boils  at  the  temperature  of  blood  heat ;  in  a  vacuum, 
it  boils  at  -40°  Fahr.  It  congeals  at  -46°  Fahr.  It  is 
slightly  soluble  in  water,  but  combines  with  alcohol  in  all 
proportions. 

Hydrochloric  Ether  (C4H5C1)  is  formed  by  the  action  of 
hydrochloric  acid  on  alcohol.  It  burns  with  an  emerald- 
green  flame,  without  smoke. 

Nitrous  Ether  (C4H5O+NOy)  is  produced  by  the  action 
of  equal  quantities  of  nitric  acid  and  alcohol,  and  resembles 
sulphuric  ether,  but  is  more  volatile. 

Oxalic  Ethtr  (C4HfO-f  C2Q3)  is  formed  by  mixing  1  part 
of  alcohol,  1  binoxolate  of  potassa,  and  2  of  SO3. 

CEnanthic  Ether  (C^^O  +  C^H^O2)  gives  to  wines  their 
peculiar  odor,  and  is  obtained  in  the  distillation  of  wine,  as 
an  oily  liquid,  which  is  a  mixture  of  oenanthic  ether  with  ex- 
cess of  cerumthic  acid.  The  ether  is  separated  by  distillation. 
It  produces  intoxication  when  inspired. 

Pyroxylic  Spirit  (C2H3O  +  HO.  32)  is  a  kind  of  ether 
formed  by  heating  wood,  and  comes  over  with  the  aqueous 
liquid.  It  has  an  alcoholic  and  aromatic  odor,  and  is  em- 
ployed by  hat-makers,  for  the  purpose  of  dissolving  shellac 
and  mastic,  to  stiffen  and  render  hats  water-proof.* 

SECT.  6.     COLORING  MATTERS. 

The  most  common  colors  in  the  vegetable  kingdom  are 
green,  yellow,  blue,  and  red.  The  greater  part  of  the  infinite 
diversity  of  colors  consists  of  different  shades  or  mixtures  of 
these.  The  coloring  matter  of  plants  is  usually  diffused 
through  other  proximate  principles.  All  vegetable  colors 
are  destroyed  by  chlorine,  and  usually  changed  by  acids  or 
alkalies. 

Lakes  are  insoluble  compounds  of  coloring  matter  with 
alumina,  or  oxide  of  iron  or  of  tin. 

*  For  a  complete  description  of  ethers,  see  Thompson,  Org.  Bodies. 


344  Vcgttable  Chemistry. 

Process.  Dissolve  alum  in  a  colored  solution,  and,  on  add- 
ing an  alkali,  (as  potassa,)  alumina  will  be  precipitated,  and, 
at  the  moment  of  separation  from  the  alum,  will  combine 
with  the  coloring  matter. 

In  dyeing,  some  colors  have  a  sufficient  affinity  for  the 
fibre  of  the  cloth  to  remain  fast  on  a  mere  immersion  of  it. 
In  many  cases,  however,  this  is  not  sufficient,  and  the  color 
would  be  removed  by  washing.  A  third  substance  is  intro- 
duced, which,  having  an  affinity  both  for  the  coloring  matter 
and  the  cloth,  fixes  the  former  permanently  to  the  latter. 
This  third  substance  is  called  the  mordant  or  basis :  those 
which  are  in  common  use  are,  Alumina  in  alum,  oxide  of 
iron  in  copperas,  and  chloride  of  tin,  which  is  converted  into 
the  oxide.  All  the  colors  of  dyed  stuffs  are  produced  from 
the  four — blue,  red,  yellow,  and  black. 

/>'///«  Dyes.  Indigo  is  the  most  important  of  these,  and  is 
obtained  from  several  species  of  a  genus  of  plants  which  arc 
cultivated  in  America  and  Asia.  The  plants  are  fermented 
and  beaten  in  water,  at  the  bottom  of  which  the  indigo  sub- 
sides. Common  indigo  contains,  in  addition  to  its  peculiar 
blue,  a  red  and  a  brown  coloring  matter,  with  some  gluten. 
Pure  indigo  sublimes  at  550°  Fahr.,  and  condenses  in  acic- 
ular  crystals.  It  is  insoluble  in.  water,  and  but  slightly 
soluble  in  boiling  alcohol;  it  is  soluble  in  sulphuric  acid.  It 
indigo  be  put  into  a  tube  with  three  times  its  weight  of  green 
vitriol,  and  an  equal  quantity  of  slacked  lime,  with  water,  the 
protoxide  of  iron  will  be  precipitated  by  the  lime  from  the 
green  vitriol,  and  the  indigo  will  be  de-oxidized  by  it,  and 
become  yellow.  Dyers  dip  their  cotton  cloth  into  it  in  this 
condition,  and  by  exposure  to  air  the  cloth  becomes  perma- 
nently blue. 

Red  Dyes.  The  most  common  substances  for  red  dyes 
are  cochineal,  lac,  Archil,  madder,  Brazil  wood,  and  logwood. 

Cochineal  is  obtained  from  an  insect  which  feeds  upon  the 
leaves  of  several  species  of  the  cactus,  and  which  is  supposed 
to  derive  this  coloring  matter  from  its  food.  It  is  very  solu- 
ble in  water,  and  is  fixed  on  cloth  by  means  of  alumina  or 


Fermentation.  345 

oxide  of  tin.  Its  natural  color  is  crimson,  but  when  jaitar- 
trate  of  potassa  is  added  to  the  solution,  it  yields  a  rich, 
scarlet  dye.  The  beautiful  pigment  called  carmine,  is  a  lake 
made  of  cochineal  and  alumina  or  oxide  of  tin.  —  T.  Archil 
is  obtained  from  a  lichen  which  grows  in  the  Canary  Islands. 
Litmus,  which  consists  of  red  coloring  matter  and  alkali,  is 
prepared  from  it.  Madder  is  the  root  of  the  rubia  tendorum, 
and  employed  for  dyeing  the  Turkey  red. 

Yellow  Dyes.  The  principal  are  quercitron  bark,  turmeric, 
saffron,  and  fustic. 

Black  Dyes.  These  are  prepared  from  the  same  ingre- 
dients as  writing  ink.  The  addition  of  logwood  and  acetate 
of  copper  gives  a  blue-black. 

SECT.  7.     FERMENTATION. 

I 

Many  vegetable  substances,  when  exposed  to  warmth  and 
moisture,  undergo  spontaneous  changes,  and  the  process  is 
called  fermentation.  It  is  most  commonly  observed  in  sub- 
stances containing  gluten,  starch,  gum,  or  sugar.  In  different 
stages  of  the  process,  sugar,  alcohol,  and  acetic  acid  are 
formed,  and  finally,  there  is  a  total  dissolution  of  the  sub- 
stance. These  stages  of  the  process  are  called  the  sac- 
charine, vinous,  acetous,  and  putrefactive  fermentations. 

Saccharine  Fermentation.  -  Starch  only  is  subject  to  this 
kind  of  fermentation.  The  quantity  of  sugar  produced*equals 
in  weight  half  of  the  starch  employed.  The  ripening  of  fruits 
has  been  regarded  as  a  kind  of  saccharine  fermentation,  in 
which  the  acid  of  the  green  fruit  is  converted  into  sugar ; 
this  change  is  caused  by  heat,  not  by  the  vitality  of  the  plant. 

Vinous  Fermentation.  When  sugar  with  water,  and  yeast 
or  some  other  ferment,  is  exposed  to  a  warm  temperature,  the 
sugar  is  converted  into  carbonic  acid  gas  and  alcohol,  in 
nearly  equal  weights  of  each.  As  starch  is  convertible  into 
sugar  by  fermentation,  if  the  process  be  continued  under  the 
above  conditions,  it  will  be  converted  into  alcohol  and  car- 
bonic acid.  All  vegetable  bodies  contain  some  substances 


346  Vegetable  Chemistry. 

which  act  as  a  ferment,  and  therefore,  by  the  addition  of 
moisture  and  regulation  of  the  temperature,  various  kinds  of 
grain  containing  starch,  and  of  ripe  fruits  containing  sugar, 
will  undergo  the  vinous  fermentation.  Thus  cider  is  formed 
from  apples,  and  beer  from  grain.  To  obtain  ardent  spirits. 
the  fermented  liquor  is  heated,  and  the  ajcohol  passes  over  by 
distillation. 

In  the  fermentation  of  bread,  the  saccharine  matter  of  the 
flour  is  resolved  into  alcohol  and  carbonic  acid  gas.  The 
latter  causes  the  dough  to  rise,  and  the  former  is  entirely  ex- 
jv  -11  (M!  by  the  heat  of  baking.  A  company  in  London  was 
formed  for  collecting  the  spirit  emitted  by  the  baking  of 
bread ;  if  the  fermentation  of  dough  be  continued,  it  under- 
goes the  change  next  described,  and  becomes  sour. 

Acetous  Fermentation.  Any  liquid  which  has  undergone 
the  vinous  fermentation,  or  pure  alcohol  with  water  and  yeast, 
exposed  to  the  air  in  a  warm  place,  undergoes  a  change,  in 
which  oxygen  is  taken  from  the  air,  and  carbonic  acid  thrown 
off.  In  place  of  alcohol,  acetic  acid  is  found  in  the  liquor. 
Thus  cider  becomes  sour  by  age,  if  exposed  to  the  air,  and 
at  length  is  converted  into  vinegar.  In  France,  wine  is  con- 
verted into  vinegar,  and  in  England,  an  infusion  of  malt. 

Acetic  arid  is  often  formed  in  the  spontaneous  decomposi- 
tion of  vegetable  substances  without  sugar.     I ir  these  < 
the  process  is  quite  different  from  the  acetous  fermentation, 
properly  so  called. 

JPutrefuit'ri-  /'/•////  nhttion.  Many  vegetable  principle 
the  acids,  oils,  resins,  and  alcohol,  are  not  subject  to  putrefar- 
tion ;  those  which  contain  oxygen  and  hydrogen  in  the  pro- 
portion to  form  water,  and  especially  those  in  which  nitrogen 
exists,  are  subject  to  this  change ;  moisture,  and  a  moderately 
warm  temperature,  are  essential  to  the  prore-s.  which  is  also 
promoted  by  air ;  water  serves  to  loosen  the  particles  of  the 
substance,  and  enables  them  to  act  freely  upon  each  other. 

The  products  of  vegetable  putrefaction  are  carbonic  acid 
gas,  and  light  carbureted  hydrogen.  In  stagnant  waters, 
which  contain  decaying  plants,  these  gases  often  rise  in  bub- 


Germination.  347 

bles,  especially  if  the  bottom  be  stirred.  Usually,  light  car- 
bureted hydrogen  is  the  most  abundant  gaseous  product. 
In  plants,  which  contain  nitrogen,  ammonia  is  generated ; 
water  is  the  principal  liquid  product,  and  vegetable  mould, 
consisting  of  charcoal,  a  little  oxygen  and  hydrogen,  the 
solid  product. 

SECT.  8.     GERMINATION. 

Germination  refers  to  the  process  by  which  a  new  plant 
originates  from  the  seed.  The  seed  consists  of  two  parts. 
The  germ,  which  is  endowed  with  the  vital  principle,  and  the 
cotyledons,  or  seed-lobes,  which  furnish  nourishment  to  the 
plant  before  it  can  derive  it  from  the  earth.  The  germ  is 
composed  of  the  radicle,  or  that  part  which  descends  into 
the  ground,  and  forms  the  root,  and  the  plumula,  which  rises 
into  the  air,  and  forms  the  stem  of  the  plant. 

The  three  conditions  necessary  to  the  germination  of  the 
plant,  are  moisture,  a  certain  temperature,  and  oxygen  gas. 
Dry  seeds  will  riot  germinate,  or,  if  moist,  germination  will 
not  take  place  at  32°,  nor  at  the  temperature  of  boiling  water, 
which  deprives  the  germ  of  its  vitality.  The  most  favorable 
temperature  is  from  69°  to  80°,  varying  with  the  nature  of 
the  plant.  Air  is  also  necessary  to  germination  ;  for  if  seeds 
are  buried  deep,  excluded  from  the  air,  they  will  never  pass 
through  this  process. 

In  the  malting  of  barley,  the  process  of  germination  may 
be  accurately  studied.  The  malting  is  done  by  exposing  the 
grain  to  moisture,  warmth,  and  air,  until  it  begins  to  germinate, 
and  then  drying  il  in  a  kiln,  where  the  temperature  ranges 
from  100°  to  160°,  or  more.  The  chemical  changes  which 
take  place  in  this  process,  are  the  following :  The  hordein, 
an  insoluble  substance,  is  converted  into  starch,  gum,  and 
sugar,  \vhich  are  soluble  and  very  nutritive  substances, 
easily  absorbed  by  the  radicle  of  the  plant ;  at  the  same 
time,  oxygen  gas  is  consumed,  and  carbonic  acid  gas  is 
given  off. 


348  Vegetable,  Chemistry. 

Growth  of  Plants.  There  are  many  points  of  resemblance 
between  the  growth  of  plants  and  of  animals;  and  also  many 
points  in  which  they  differ.  The  chemical  changes  which 
the  sap  undergoes,  by  what  is  called  the  respiration  of  plant*, 
is  probably  very  analogous  to  what  takes  place  in  the  blood 
of  animals  ;  with  this  difference,  however,  that  animals  cpn- 
sume  oxygen,  and  throw  off  carbonic  acid,  while  vegetables 
absorb  carbonic  acid  and  yield  oxygen  gas,  provided,  in  the 
latter  case,  they  are  exposed  to  sunshine.  In  the  night,  the 
reverse  often  takes  place;  light  seems  necessary  to  the  color- 
ing of  plants,  and  to  their  health  and  perfection. 

Food  of  Plants.  Plants  derive  their  food,  for  the  most 
part,  from  the  earth.  The  soil  generally  consists  of  siliceous 
earth,  clay,  lime,  and  sometimes  magnesia,  mixed  with  the 
remains  of  animal  and  vegetable  substances.  The  watt T 
passes  through  it,  and  dissolves  the  salts  contained  in  it,  ;m<l 
absorbs  the  gaseous,  extractive,  and  other  matters,  which  the 
process  of  decomposing  animal  and  vegetable  remains  pro- 
duces. It  is  then  absorbed  by  the  roots  of  the  plant,  and  is 
conveyed  to  the  leaves,  where  it  is  fitted  to  nourish  the  plant. 

There  are  some  plants,  however,  which  do  not  <h  1 1\<  flu  ir 
nutrition  from  this  source,  as  they  are  found  to  vegetate  in 
distilled  water,  and  to  grow  for  some  time  when  merely  sus- 
pended in  the  air.  This  is  accounted  for  on  the  supposition 
that  carbonic  acid  is  the  proper  food  for  plants.  This  sub- 
stance is  obtained  -from  the  atmosphere,  absorbed  by  the 
leaves  of  the  plant,  and  appropriated  to  its  nourishn:« >nt. 
When  plants  are  burned,  their  ashes  contain  various  salts 
which  must  have  been  derived  from  the  earth. 

The  peculiar  vegetable  substances  which  are  formed  from 
sap,  appear  to.  be  under  the  control  of  the  vital  principle, 
over  which  the  ordinary  agents  of  chemical  changes  have  but 
little  power. 


Animal  Chemistry.  349 

CHAPTER    V. 

ANIMAL   CHEMISTRY. 

With  the  exception  of  the  oils,  animal  substances  usually 
contain  a  large  portion  of  nitrogen,  and  have  a  strong  ten- 
dency to  putrefaction.  Their  proximate  principles  are  much 
less  numerous  than  those  of  vegetables.  In  addition  to  car- 
bon, hydrogen,  oxygen,  and  nitrogen,  sulphur,  phosphorus, 
iron,  earthy  and  saline  matters  are  usually  present  in  animal 
bodies. 

SECT.  1.      PROXIMATE  PRINCIPLES  NEITHER  ACID  NOR 
OLEAGINOUS. 

Fibrin.  This  principle  is  the  basis  of  the  muscles,  and  is 
found  abundantly  in  the  blood.  It  is  a  white,  insipid  solid 
when  pure,  and  easily  putrefies.  When  subjected  to  the 
action  of  nitric  taid,  it  throws  off  a  large  quantity  of  nitrogen, 
and  with  acetic  acid  forms  a  jelly. 

Albumen.  Albumen  exists  in  a  solid  state  in  the  skin, 
glands,  and  vessels,  and  in  a  liquid  state  in  the  serum  of 
blood,  the  fluid  of  dropsy,  and  the  white  of  eggs.  The  latter 
substance  consists  almost  solely  of  it.  When  liquid,  it  is 
coagulated  by  heat,  as  in  the  boiling  of  an  egg,  or  by  alco- 
hol and  the  stronger  acids.  Corrosive  suhjimate  is  a  very 
delicate  test,  producing  a  milkiness  in  water,  which  contains 
ffirW  albumen. 

Gelatin.  This  substance  is  abundant  in  the  solid  parts  of 
animals,  in  the  skin,  cartilages,  membranes,  and  bones.  It  is 
easily  soluble  in  boiling  water,  and  forms  a  bulky  jelly  on 
cooling.  One  part  in  100  of  water,  will  render  the  whole 
solid  when  cool.  The  jelly  is  a  hydrate  of  gelatin;  and,  if 
the  water  be  expelled  by  a  gentle  heat,  it  may  be  preserved 
for  any  length  of  time.  This  is  glue,  which  is  prepared 
from  the  ears,  skins,  and  hoofs  of  animals.  Isinglass  is  the 
purest  variety,  prepared  from  the  sounds  offish. 
30 


350  Animal  Chemistry. 

Osmazome  exists  in  the  muscular  fibres.     It  is  very  insolu- 
ble, and  is  supposed  to  give  to  broth  its  peculiar  flavor. 


SECT.  2.     ANIMAL  ACIDS. 

Many  acids  are  found  in  animals,  which  are  found  also  in 
the  mineral  and  vegetable  kingdoms  ;  such  are  the  sulphuric, 
hydrochloric,  phosphoric,  and  acetic  acids.  Those  which 
are  peculiar  to  animals,  are  very  few,  and  are  derived  chiefly 
from  urine,  or  from  oils  and  fats ;  of  the  latter  are  stearic, 
oleic,  and  margaric  acids.  Formic  acid  is  a  remarkable  acid, 
found  in  ants,  and  is  ejected  by  them  when  they  are  irritated. 


SECT.  3.     ANIMAL  OILS  AND  FATS. 

These  substances  are  very  similar  to  the  vegetable  oils, 
and  may  be  used  either  in  the  manufacture  of  soap,  or  for 
giving  light. 

Train  Oil  is  obtained  from  the  blubber  of  the  right  whale, 
and  is  much  inferior  for  lights  to  spermaceti. 

Spermaceti  Oil  is  obtained  from  the  blubber  of  the  sperm 
whale,  and  from  a  large  cavity  in  the  head,  from  whirh 
twelve  or  fifteen  barrels  of  liquid  oil  are  sometimes  dipped 
out.  This  substance  is  strained  through  stout  bags,  which 
are  subjected  to  a  strong  pressure.  The  solid  which  remain- 
is  spermaceti  f  of  which  candles  are  manufactured,  and  the 
liquid  is  the  spermaceti  oil.  As  the  oil  is  more  liquid  in  hot 
weather,  summer-strained  oil  contains  more  spermaceti,  and 
b  given  quantity  will  therefore  produce  more  light,  and  burn 
less  freely  than  winter-strained  oil ;  the  latter  is  usually  pre- 
ferred, as  giving  a  clearer  light,  and  as  being  less  affected  by 
cold,  but  it  is  much  less  economical. 

Hog's  Lard  and  Suet  are  well-known  substances,  differing 
much  in  respect  to  their  point  of  fusion. 

Animal  oils  and  fats  are  not  proximate  principles,  but  con- 


Complex  Animal  Substances.  351 

sist  chiefly  of  stearine  and  margarine,  which  are  solid  at 
common  temperatures,  and  olcinc,  which  is  liquid. 

Soaps.  When  any  of  the  animal  or  vegetable  oils  or  fats 
are  boiled  with  a  solution  of  potassa  or  soda,  the  former  are 
converted  into  margaric,  oleic,  or  stearic  acids,  and  another 
principle  called  glycerine.  The  acids  combine  with  the 
ul kali,  and  form  soap.  The  compounds  which  they  form 
are  soluble  in  pure  water,  but  in  solutions  containing  salts  of 
lime,  oxide  of  lead,  and  many  other  metallic  compounds, 
they  combine  in  preference  with  these  oxides,  and  form  in- 
soluble compounds.  Hence  hard  water,  containing  salts  of 
lime,  curdles  soap. 

Ambergris,  found  floating  on  the  ocean,  is  supposed  to  be 
a  concretion  formed  in  the  stomach  of  the  sperm  whale. 


SECT.  4.     COMPLEX  ANIMAL  SUBSTANCES. 

Blood. 

Blood  consists  of  a  liquid,  through  which  are  diffused  red 
globular  particles.  The  liquid  portion  consists  of  water, 
holding  in  solution  fibrin,  with  albumen,  and  saline  and  oily 
matters.  When  set  at  rest,  it  coagulates,  forming  a  jelly. 
The  red  globules  are  also  compound,  containing  fibrin  and 
the  coloring  matter.  In  mammiferous  animals,  these  globules 
are  spherical ;  but  in  birds,  reptiles,  and  fishes,  they  are 
ellipsoidal. 

When  blood  is  set  at  rest,  it  does  not  separate  into  the  two 
parts  above  mentioned,  but  into  a  red  coagulum  called  the 
clot  and  the  serum,  which  is  a  yellowish  liquid. 

The  saline  substances  contained  in  the  blood  are  carbon- 
ates, phosphates,  and  sulphates  of  potassa  and  soda.  It  con- 
tains also  chloride  of  sodium,  (common  salt,)  chloride  of 
potassium,  and  sesquioxide  of  iron.  More  than  j  of  the 
blood  is  water ;  the  coloring  matter  is  in  the  ratio  of  125 
parts  in  1000,  and  albumen,  about  67  in  1000.  The  propor- 


352  Animal  Chemistry. 

tions  vary  somewhat,  even  in  the  same  person,  at  different 
times. 

The  following  table,  by  M.  Le  Canu,  represents  the  com- 
position of  the  blood  as  derived  from  two  careful  analyses :  — 

Water, 780.145        785.590 

Fibrin,       .         .         .*.-.'<>.         .         .  2.100 

Coloring  matter,  .  .  •%-,  *  .- .  .  133.000  ll'.'.i.Ji; 
Albumen,  .  .  "  .  .-  .  .  ,s"  65.090  69.4 15 
Crystalline  fatty  matter,  .  .  -  .*  >*  ';'  2.43  4.300 

Oily  matter, 1  :Ut) 

Extractive  matter  soluble  in  water  and  alcohol, 

Al'uinicii  mi:iliined  with  soda,  .         .         .  1.265 

Chloride  of*  sodium,  .     .  . 

"       of  potassium,       .  . 

CarbonaU>s5,  .        .  8.370  7.304 

Phosphates  V  of  soda  and  potansa, 
Sulphates    ) 

Carbonates  of  lime  and  magnesia, 

Phosphates  of  lime,  magnesia,  and  iron,  £          .  2.100  1.414 

Peroxide  of  iron. 
Loss,         .;....        .        .      " .        .  2.400  2.586 

1000.000      1000.000 


ron,? 


The  changes  which  are  effected  on  the  blood  by  respira- 
tion, are  due  to  the  oxygen  of  the  atmosphere.  The  dark 
blood  of  the  veins  enters  the  lungs,  and,  being  there  exposed 
to  the  action  of  the  air  through  a  thin  membrane,  absorbs 
oxygen,  throws  off*  or  forms  carbonic  acid  gas,  and  passes 
into  the  arteries  with  a  bright  red  color.  A  large  quantity 
of  carbonic  acid  is  emitted  by  the  lungs,  and  hence  the  ne- 
cessity of  a  free  circulation  of  air  in  small  or  crowded  room.-. 

Animal  Heat.  There  is  a  striking  analogy  between  the 
process  of  combustion  and  respiration.  In  both  cases,  oxy- 
gen is  consumed,  and  carbonic  acid  produced.  This  fact  led 
Dr.  Black  to  infer  that  the  heat  generated  in  the  animal  sys- 
tem was  derived  from  the  change  which  takes  place  in  the 
lungs.  That  the  development  of  animal  heat  is  dependent 
upon  respiration,  is  a  matter  of  easy  demonstration;  but  how 
the  effect  takes  place,  has  not  been  satisfactorily  explained. 
In  those  animals  which  consume  a  small  quantity  of  oxygen, 
the  temperature  of  their  bodies  varies  with  the  surround in«r 
medium,  and  are  called  cold-blooded ;  but  in  those  that  con- 


Complex  Animal  Substances. 

eume  a  larger  quantity  of  oxygen,  the  temperature  is  nearly 
uniform,  whatever  be  the  temperature  of  the  medium.  They 
are  hence  called  warm-blooded.  The  temperature  of  the 
same  animal  varies  often,  according  as  the  respiration  is  slug- 
gish or  rapid. 

To  account  for  animal  heat,  Dr.  Crawford  proposed  the» 
first  consistent  theory,  which  is  founded  on  the  supposition 
that  the  blood,  when  purified  by  the  oxygen  of  the  air,  has 
its  capacity  increased  for  caloric;  and  hence  the  heat  pro- 
duced in  the  lungs  by  the  consumption  of  the  oxygen,  enters 
into  an  insensible  state,  in  the  arterial  blood.  As  this  blood 
circulates  through  the  system  and  enters  the  veins,  it  loses  its 
capacity,  and  gives  out  its  caloric.  But  Dr.  Davy  denies  that 
there  is  any  difference  between  the  capacity  of  venous  and 
arterial  blood.  If,  however,  we  suppose  that  the  oxygen  does 
not  combine  with  the  carbon  in  the  lungs,  but  in  the  course 
of  circulation,  there  would  be  heat  developed  in  all  parts  of 
the  system;  and  this  view  would  account  for  the  facts,  irre- 
spective of  the  different  capacities  of  the  two  kinds  of  blood. 

The  influence  of  the  vital  principle,  doubtless,  has  much  to 
do,  both  in  the  development  and  preservation  of  animal  heat. 
The  nerves  have  been  supposed  also  to  possess  a  specific 
power  of  generating  heat ;  but,  whatever  be  the  cause,  it  is 
evident  that  the  arterialization  of  the  blood  does  not  account 
for  all  the  heat  of  the  animal  system,  from  the  fact  that  a 
healthy  animal  imparts  more  heat  to  surrounding  bodies, 
than  could  be  produced  froin  this  source  alone. 

Saliva.  This  liquid  contains  only  seven  parts  of  solid 
matter  in  a  thousand.  It  contains  chloride  of  potassium, 
sulphate,  phosphate,  acetate  and  carbonate  of  potassa,  with 
some  other  salts.  It  forms  a  soft,  pulpy  mass  with  the  food 
in  mastication,  preparing  it  for  more  easy  digestion. 

Gastric  Juice.  This  fluid  taken  from  an  empty  stomach 
has  a  saline  taste,  and  is  neutral.  But  when  any  substance 
enters  the  stomach,  acid  is  secreted.  Both  hydrochloric  and 
acetic  acids  are  formed.  All  nutritious  substances  are  dis- 
solved by  this  juice,  and  converted  into  a  pulpy  mass  caJled 
30* 


854  Animal  Chemistry. 

chyle.  It  does  not  act  on  living  substances,  or  the  stomach 
itself  would  be  dissolved,  as  sometimes  is  the  fact  after  death. 
Its  solvent  power  is  due  to  the  acids,  which  are  greatly  aided 
by  the  temperature  of  the  stomach.  By  taking  magnesia,  the 
acids  are  neutralized,  and  the  digestive  power  suspended  for 
the  time. 

Bile.  The  bile  is  a  yellow  or  greenish,  nauseous  liquid, 
of  which  I  are  water,  and  the  remainder  a  peculiar  bitter 
principle,  called  picromal,  with  resin,  and  several  salts.  Th< 
bile  stimulates  the  intestinal  canal,  and  assists  in  converting 
the  chyme  into  chyle. 

Chyle.  This  is  a  white  fluid  resembling  milk.  It  contains 
about  90  per  cent,  of  water  ;  of  the  other  constituents,  albu- 
men is  most  abundant. 

Milk:  This  liquid  is  well  known  to  consist  of  cream, 
curd,  and  whey.  100  parts  of  cream,  of  specific  gravity 
1.0244,  contain  only  4.5  parts  of  butter;  of  the  remainder, 
92  are  whey,  and  3.5  curd.  The  coagulation  in  sour  milk  is 
produced  by  the  generation  of  acetic  acid,  which,  in  com- 
mon with  acids  generally,  separates  the  curd  from  the  whey. 
The  same  effect  is  caused  by  rennet  prepared  from  a  c:ilf  s 
stomach,  which  is  impregnated  with  the  gastric  juice,  and 
therefore  contains  acid.  Milk  is  of  course  curdled  when 
taken  into  the  stomach. 

Lymph  is  a  peculiar;  limpid,  transparent  liquid,  which 
moistens  the  cellular  membrane,  and  collects  abundantly  in 
some  dropsical  affections.  It  consists  chiefly  of  water,  with 
hydrochlorate  of  soda  and  albumen. 

The  humors  of  the  eye  contain  more  than  80  per  cent,  of 
water ;  the  other  ingredients  are  albumen,  muriate  and  acetate 
of  soda,  pure  soda,  and  an  animal  matter  like  curd,  which 
gives  it  a  milky  appearance. 

The  tears  contain  pure  soda,  chloride  of  sodium,  and  phos- 
phate of  soda,  with  water,  and  an  animal  matter  analogous 
to  albumen. 

Mucus  is  a  fluids  ecreted  by  the  raucous  surfaces,  as  the 
nose. 


Complex  Animal  Substances.  355 

Pus  is  a  liquid  matter  secreted  by  an  inflamed  and  ulcera- 
ted surface.  Its  characteristic  ingredient  resembles  albumen. 

Sweat  is  the  vapor  which  constantly  passes  off  from  the 
skin,  and  consists  mostly  of  water,  mixed  with  a  little  jnuriate 
of  soda,  and  free  acetic  acid. 

Urine  differs  from  most  animal  fluids  in  serving  no  ulterior 
purpose  in  the  animal  economy.  It  is  an  excretion  consisting 
of  substances  which  would  prove  injurious  to  life  and  health. 
The  urine  is  separated  by  the  kidneys  from  the  blood,  and 
consists  of  a  great  variety  of  substances,  such  as  water  and 
urea,  which  are  the  principal,  uric  acid,  lactic  acid,  lactate  of 
ammonia,  mucus,  sulphates  of  potassa  and  of  soda,  phos- 
phates of  soda  and  of  ammonia,  muriates  of  soda  and  of  am- 
monia, earthy  matters  with  a  trace  of  fluate  of  lime,  and  sili- 
ceous earth. 

Eggs.     The  shell  of  an  egg  is  about  -fa,  the  white  -ft, 

.and  the  yolk  T3^  of  the  whole.     The  shell  consists  chiefly  of 

-carbonate  of  lime ;  and  the  white,  of  albumen,  with   a  little 

sulphur.      The   yolk   contains   phosphorus,    which  supplies 

phosphoric  acid  for  forming  the  bones  of  the  chicken. 

Bones.  Bones  contain  about  £  of  animal  matter,  £  of 
phosphate  of  lime,  -^  of  carbonate  of  lime,  with  a  little  fluoride 
of  calcium,  and  some  other  salts.  Teeth  have  the  same  com- 
position, but  the  enamel  contains  78  per  cent,  of  phosphate 
of  lime.  The  shells  of  crustaceous  animals,  as  lobsters  and 
crabs,  consist  of  carbonate  and  phosphate  of  lime,  with  anir 
mal  matter ;  but  the  shells  of  molluscous  animals,  or  true 
shells,  as  of  the  oyster,  snail,  etc.,  consist  almost  entirely  of 
carbonate  of  lime  and  animal  matter. 

Horn  differs  from  bone  in  containing  only  a  trace  of  earth. 
The  composition  of  the  nails,  hoofs,  and  cuticle  of  animals  is 
similar  to  horn. 

Tendons  are  composed  almost  wholly  of  gelatin. 

The  true  skin  has  nearfy  the  same  composition.  Membranes 
and  ligaments  contain  in  addition  some  substance  which  is 
insoluble  in  water,  and  is  similar  to  coagulated  albumen. 

Hair  contains  a  peculiar  animal  substance,  insoluble  in 
water  at  212°,  but  soluble  in  a  solution  of  potassa.  It  also 


356  Analytical  Chemistry. 

contains  an  oil,  which  gives  the  peculiar  color  of  the  hair, 
sulphur,  upon  which  the  nitrate  of  oxide  of  silver  acts  in  stain- 
ing it,  together  with  silica,  iron,  manganese,  and  carbonate 
and  phosphate  of  lime. 

Woo/  and  feathers  are  similar  in  composition  to  hair. 

Silk  is  covered  with  a  peculiar  varnish,  which  amounts  to 
about  23  per  cent. 

Muscle.  The  lean  flesh  of  animals  consists  essentially  of 
fibrin,  with  numerous  other  ingredients,  such  as  albumen, 
gelatin,  a  peculiar  extractive  matter  called  osmazomc,  fat,  and 
salts.  « 


CHAPTER    VI. 

ANALYTICAL  CHEMISTRY. 

It  is  the  object  of  analytical  chemistry  to  point  out  the 
method  of  separating  compound  bodies  into  their  simple 
elements.  As  the  subject  is  extensive,  a  few  things  only 
will  be  inserted  here,  in  order  to  give  the  student  an  idea  of 
the  nature  of  the  procees. 

SECT.  1.     ANALYSIS  OF  MIXED  GASES. 

1.   Gaseous  Mixtures  containing  Oxygen.       f^gt  102. 
The  best  process  by  which  oxygen  gas  may 
be  withdrawn  from  gaseous  mixtures,  is  by    . 
means  of  hydrogen  gas.     In  case  of  the  air,  £ 
a  given  portion  is  taken,  and  rather  more 
hydrogen  added  than  is  sufficient  to  com- 
bine with  the  oxygen.     The  mixture  is  then 
introduced  into  a  strong  glass  tube,  or  eudi- 
ometer, (Fig.  102,)  over  water  or  mercury, 
and  exploded  by  the  electric  spark.     The 
total  diminution  in  volume,  divided  by  three, 
will   give  the   quantity  of  oxygen  present. 
Instead  of  exploding  the  gases,  they  may  be 
made  to  combine  slowly,  by  introducing  into  the  mixture 
platinum  sponge. 


Analysis  of  Minerals.  357 

2.  Gaseous  Mixtures  containing   Nitrogen.     As  the    air 
contains  only  oxygen  and  nitrogen,  when  other  substances 
are  withdrawn,  if  its  oxygen  is  determined,  the  quantity  of 
its  nitrogen  may  be  easily  known.     The  only  mode  of  ascer- 
taining the  quantity  of  nitrogen  in  any  mixture,  is  to  vvith- 
<lra\v  the  other  gases  from  it. 

3.  Gaseous  Mixtures  containing  Carbonic  Acid.      When 
cnrbonic  is  the  only  acid  gas  present,  as  is  the  case  with  air 
and  organic  compounds,  the  process  consists  merely  in  ab- 
sorbing this  gas  by  lime  water,  or  a  solution  of  caustic  potassa, 

4.  Gaseous  Mixtures  containing  Hydrogen  and  other  In- 
flammable Bodies.     The  quantity  of  hydrogen,  when  mixed 
with  nitrogen,  oxygen,  or  atmospheric  air,  is  ascertained  by 
adding  a  portion  of  oxygen,  and  exploding  the  mixture.     The 
quantity  of  other  inflammable  bodies,  such  as  carbonic  oxide, 
light  carbureted  hydrogen,  or  olefiant  gas  mixed  with  nitro- 
gen, is  determined  by  adding  a  sufficient  quantity  of  oxygen, 
and  detonating  the  mixture.     The  diminution  of  volume  in- 
dicates the  quantity  of  hydrogen  contained  in  the  mixture, 
and  by  withdrawing  the  carbonic  acid,  the  quantity  of  car- 
bon may  be  known. 

SECT.  2.     ANALYSIS  OF  MINERALS. 

In  order  to  analyze  any  mineral  compound,  the  first  object 
is  to  bring  the  body  into  a  state  of  solution.  This  is  effected, 
generally,  by  water  or  acids;  but  in  cases  where  the  sub- 
stance  is  not  dissolved  by  these,  it  is  made  into  a  paste,  with 
three  or  four  times  its  weight  of  fused  borax,  potassa,  soda, 
baryta,  or  their  carbonates,  and  subjected  to  a  strong  heat, 
in  a  platinum  or  silver  crucible.  By  this  means,  the  alkali 
combines  with  one  or  more  of  the  constituents  of  the  min- 
eral, and  then  it  is  in  a  state  to  be  acted  upon  by  acids. 

1.  Analysis  of  Minerals  soluble  in  Jltids  with  Effervescence, 
Reduce  the  mineral  to  a  fine  powder,  and  boil  it  for  two  hours  in 
the  acid  which  holds  it  in  solution,  diluted  with  five  or  six  times  its 
bulk  of  water.     This  solution  may   contain  lime,    baryta,    magnesia, 
fitrontia,  alumina,  and  oxides  of  rnetals. 

1.  Add  to  a  small  portion  of  the  liquor,  diluted  with  20  parts  of  water, 


358 


Analytical  Chemistry. 


sulphnte  of  soda,  and  if  a  precipitate  appear,  baryta,  or  strontia,  or 
both,  are  present.  Nitric  acid,  diluted  with  an  equal  weight  of  water, 
will  dissolve  the  strontia,  if  present,  in  the  separated  precipitate,  but 
will  not  act  upon  the  baryta. 

2.  Add  to  a  portion  of  the  liquid,  ferrocyanate  of  potassa,  and  if 
metallic  oxides  are  present,  a  precipitate  will  be  thrown  down,  the 
color  of  which  will  probably  show  the  kind  of  metal. 

3.  Carbonate  of  potassa   will  precipitate   the  lime,  magnesia,  and 
alumina,  from  which  the  alumina  may  be  dissolved  by  a  solution  of 
potassa,  and  precipitated  again  by  dilute  hydrochloric  acid. 

Having  precipitated  Uie  alumina,  dilute  hydrochloric  acid  will  re- 
dissolve  what  remains,  from  which  oxalate  of  ammonia  will  precipitate 
the  lime. 

Add  to  the  remaining  liquid,  in  successive  portions,  carbonate  of 
ammonia  and  phosphate  of  soda,  and  magnesia,  if  present,  will  be  pre- 
cipitated. 

IL  Analysis  of  Mineral*  which  an  insoluble  in  Jlcids. 
Heat  a  mixture  of  1  part  of  the  mineral  to  3  of  fused  borax,  for  throe 
hours,  in  a  platinum  crucible  ;  dissolve  the  content*  by  digesting  the 
whole  in  hydrochloric  acid,  for  several  hours;  add  carbonate  •<• 
inonia,  and  the  whole  will  be  precipitated;  filter  and  wash  the  pn  capi- 
tate, to  separate  the  borax,  and  re-dissolve  in  hydrochloric  a<  id      If  any 
matter  remain,  it  is  silica.     The  solution  may  then  be  tested  as  in  the 
former  case. 

HI.  Analysis  of  Minerals  containing  Carbonate  of  Lime,  Silica, 
Oxide  of  Iron,  and  Magnesia. 

1.  Reduce  the  mineral  to  a  fine  powder,  and  weigh  out  a  given  por- 
tion, as  1000  grs. ;  dry  the  powder  just  up  to  browning  paper;  the  loss 
of  weight  is  water. 

2.  Having  put  the  powder  into  a  flask, 
to  which  a  cork  with  a  bent  tube  it  at- 
tached, (Fig.  103,)  pour  upon  it  water,  and 
then  hydrochloric  acid,  quickly  inserting 
the  stopper,  and  placing  the  tube  in  a  ves- 
sel  of  baryta   water ;  carbonic   acid    will 
escape  through  the  tube  into  the  solution 
of  baryta,  and  form  carbonate  of  baryta, 
which  will  be  in  fine  powder.    Filter  and 
dry  the  residue ;  the  weight  will  give  the 
quantity  of  carbonic  acid,  22  parts  of  acid 
being  combined  with  78  of  baryta. 

3.  Dilute  the  liquor  in   the    flask  with 
.water,  throw  it  upon  a  filter,  and  wash; 

the  insoluble  matter  is  silica. 

4.  The  washings  of  the  filter  contain  a  solution  of  the  oxide  and  lime. 
Precipitate  the  oxide  with  excess  of  ammonia;  filter,  wash,  dry,  and 
weigh;  from  this  the  iron  may  be  estimated,  as  the  oxide  will  contain 
12  parts  of  oxygen,  9  of  water,  and  2d  of  iron.     Oxalate  of  ammonia  will 
precipitate  the  lime  from  the  remaining  liquor,  which  being  fifN-n-d. 
washed,  and  burned  in  a  crucible,  lime  only  will  remain.  The  magnesia, 
which  is  still  in  solution,  may  be  precipitated  by  carbonate  of  ammonia 
in  excess,  and  by  adding  phosphate  of  soda;  filter,  dry,  and  weigh  ;  100 
parts  will  contain  40  of  pure  magnesia. 

77te  Compounds  of  Silica,  Alumina,  and  Iron,  are  decomposed  by  al- 


Fig.  103. 


Analysis  of  Metallic  Ores.  359 

kaline  carbonates,  at  a  red  heat.     For  further  processes,  see  Turner's 
Chemistry,  or  Rose's  Analytical  Chemistry. 

IV.    Tests  of  Metallic  Ores. 

1.  Ores  of  Antimony  are  first  dissolved  in  nitrohydrochloric  acid,  which 
takes  up  all  the  sulphur.     The  oxide  of  antimony  is  then  precipitated 
by  simply  adding  water. 

2.  Ores  of  Lead  are  dissolved  in  nitric  acid,  with  the  exception  of 
the  sulphur,  which  may  be  separated  by  a  filter ;  add  to  the  solution 
carbonate  of  soda,  and  carbonate  of  lead  will  be  thrown  down.     The 
silver,  if  present,  will  also  be  precipitated,  and  may  be  separated  from 
tlit>  carbonate  of  lead  by  liquid  ammonia,  which  holas  it  in  solution. 

3.  Orr.s-  of  Mercury  are  mixed  with  iron-filings  or  lime,  and  exposed, 
in  an  iron  retort,  to  a  strong  heat;  when  the  mercury  will  distil  over. 

4.  Ores  of  Zinc  may  be  boiled  in  nitric  acid  to  dry  ness,  and  the  pro- 
cess repeated.     If  iron  is  present,  it  will  be  peroxidated.  and  dilute 
nitric  acid  will  dissolve  out  the  zinc ;  filter  the  solution,  and  add  liquid 
ammonia  in  excess  ;  the  lead,  if  present,  will  be  precipitated,  and  the 
zinc  will  remain  in  solution.     The  oxide  of  zinc  is  obtained  by  boiling 
this  solution  to  dryness. 

5.  Ores  of  Tin.     As  these  ores  usually  contain  silica,  they  must  be 
first  treated  like  an  earthy  mineral  not  soluble  in  acids.     The  tin  will 
be  detected  by  forming  a  purple  solution  with  the  chloride  of  gold. 

6.  Ores  of  Iron.     The  peroxide  of  iron  is  first  rendered  soluble  by 
heating  it  for  an  hour  with  one  eighth  of  its  weight  of  powdered  char- 
coal.    The  black  oxide  is  soluble  in  dilute  hydrochloric  acid.     If  phos- 
phate of  iron  is  present,  it  may  be  detected  by  adding  to  the  hydrochloric 
solution  10  parts  of  water,  (which  has  been  boiled,  to  separate  the  air,) 
placing  it  in  a  bottle  corked  tight,  and  set  aside  for  6  or  8  days,  when 
the  phosphate  of  iron  will  be  precipitated.     The  filtered  solution  may 
contain  oxides  of  iron,  manganese,  and  zinc,  all  of  which  are  thrown 
down  by  carbonate  of  soda.     The  oxide  of  zinc  may  then  be  separated 
by  ammonia,  and  the  oxide  of  manganese  by  acetic  acid.     The  oxide 
of  iron  will  then  remain,  and,  after  being  ignited,  will  contain  72  per 
cent,  of  the  pure  metal. 

7.  Ores  of  Copper  are  boiled  dry  with  five  times  their  weight  of  sul- 
phuric acid.     The  sulphate  of  copper  which  is  formed  is  dissolved  by 
water,  and  the  metallic  copper  precipitated  by  a  plate  of  clean  iron. 

8.  Ores  of  Silver  are  dissolved  by  nitric  acid.     Immerse  in  the  solu- 
tion a  plate  of  polished  copper,  and  the  silver  will  be  precipitated  upon 
it,  if  no  lead  is  present.     Common  salt  will  throw  down  the  chloride 
of  silver. 

9.  Ores  of  Gold  and   Platinum  are  dissolved  in   nitrohydrochloric 
acid  ;  the  solution  is  then  evaporated  until  nitrous  acid  fumes  cease  to 
appear,  and  the  odor  of  chlorine  is  perceptible  ;  the  product  is  dissolved 
in  water,  and  a  solution  of  hydrochlorate  of  tin  added,  when  a  purple 
precipitate  will  be  thrown  down,  if  gold  is  present.     If  platinum  is  in 
the  mixture,  it  may  be  precipitated  by  hydrochlorate  of  ammonia. 

When  the  solution  contains  gold  with  other  metals,  the  sulphate  of 
the  protoxide  of  iron  precipitates  the  gold  with  the  palladium,  mercury, 
and  silver,  if  present.  As  silver  is  most  frequently  present,  common 
salt  should  be  added  previous  to  the  sulphate  of  iron,  to  precipitate  it. 

Earthy  Sulphates.  The  sulphate  of  lime  is  easily  analyzed  by  boil- 
ing it  for  fifteen  or  twenty  minutes  in  a  solution  of  twice  its  weight  of 
carbonate  of  soda.  The  carbonate  of  lime  and  sulphate  of  soda  are 


360  Analytical  Chemistry. 

formed  by  doable  decomposition.  The  sulphate  of  soda  is  then  de>- 
composed  by  chloride  of  barium,  and  the  carbonate  of  lime  analyzed  in 
the  usual  way.* 

SECT.  3.     ANALYSIS  OF  MINERAL  WATERS. 

The  purest  water  is  obtained  by  distillation.  Rain  water, 
or  that  from  fresh  fallen  snow,  is  next  in  purity. 

Well  and  spring  water  contain  some  salts,  which  are  de- 
rived   from   the  soil  through  which  the  rain  water  j> 
hence  the  purity  of  water  will  depend  upon  the  nature  of  the 
soils.     If  it  is  filtered  through  primitive  strata,  such  as  «ir;m- 
ite,  it  will  contain  few  salts,  but  if  through   secondary  - 
such  as  limestone  and  gypsum,  it  becomes  impregnated  with 
various  other  substances,  and  is  mineralized.     Lame  renders 
it  hard. 

The  different  kinds  of  mineral  water  are  ttridulmtt,  ti/ka- 
line,  chalybeati,  fiilp/inrtttd.  .^i/iin  ,  and  si/icrnus  s/irin^s. 

1.  In  acidulous  springs,  of  which  those  of  Saratoga  and 
Seltzer  are  examples,  the  acidity  is  due  to  tin-  < -arhonic  acid 
with  which  their  waters  are   impregnated;  they   frequently 
contain  protoxide  of  iron,  carbonates  of  lime,  magnesia,  and 
other  saline  compounds.    The  carbonic  acid  is  easily  expelled 
by  heat,  and  may  be  collected  over  mercury. 

2.  Alkaline  springs  are  very  rare;  they  generally  contaiir* 
a  free  or  carbonated  alkali. 

:*.  Chalybeate  springs.  These  waters  are  character i/.ed  by 
styptic,  inky  taste,  and  by  striking  a  black  color  with  ini',- 
sion  of  gall-nuts.  The  iron  is  either  combined  with  hydnv- 
chloric  and  sulphuric  acids,  or  exists  in  the  form  of  proto- 
carbonate,  held  in  solution  by  free  carbonic  acid.  On 
exposure  to  the  air,  the  protoxide  is  oxidized,  and  the  hy- 
drated  peroxide  subsides  as  an  ochreous  deposit,  which  is 
commonly  found  in  the  vicinity  of  chalybeate  springs.  —  T. 

4.  Saline  springs  owe  their  properties  to  saline  compounds, 
such  as  sulphates  and  carbonates  of  lime,  magnesia,  and  so- 
da, and  the  chlorides  of  calcium,  magnesium,  and  sodium. 

.In  the  analysis  of  saline  springs,  the  first  object  is  to  ascer- 
tain the  nature  of  the  ingredients.  Hydrochloric  acid  is 
detected  by  nitrate  of  oxide  of  silver,  sulphuric  acid  by  chlo- 
ride of  barium;  and  if  an  alkaline  carbonate  be  present,  the 
precipitates  will  contain  a  carbonate  of  oxide  of  silver,  or  of 
baryta.  Lime  and  magnesia  may  be  detected,  the  former  by 

*  For  other  sulphates,  see  Turner,  p.  241. 


Test  Tubes, 


361 


oxalate  of  ammonia,  and  the  latter  by  phosphate  of  ammonia. 
Potassa  is  known  by  the  action  of  chloride  of  platinum.  To 
detect  soda,  the  water  should  be  evaporated  to  dryness,  the 
deliquescent  salts  removed  by  alcohol,  and  the  matter  insolu- 
ble in  that  menstruum  taken  up  by  a  small  quantity  of  water, 
and  allowed  to  crystallize  by  spontaneous  evaporation.  The 
salt  of  soda  may  then  be  recognized  by  the  rich  yellow  color 
which  it  communicates  to  flame.  If  the  presence  of  hydri- 
odic  acid  be  suspected,  the  solution  is  brought  to  dryness,  the 
soluble  parts  dissolved  in  two  or  three  drachms  of  a  cold  so- 
lution of  starch,  and  strong  sulphuric  acid  slowly  added.  —  T. 
Sulphurated  springs  are  characterized  by  their  odor,  and 
by  the  brown  precipitate,  which  a  salt  of  lead  or  silver  occa- 
sions. This  is  owing  to  the  hydrosulphuric  acid  gas  which 
they  contain.  The  quantity  of  gas  is  ascertained  by  boiling 
the  water,  which  expels  it. 

To  detect  Hydrosutphuric  Jlcid.  Take  a  flask, 
with  a  tube  bent  twice  at  right  angles,  one  end 
of  which  dips  into  a  solution  of  acetate  of  lead. 
(Fijr.  104.)  Introduce  the  water  into  the  flask, 
and  apply  heat  until  it  boils.  The  gas  will  be 
driven  oft,  and  decompose  the  acetate,  forming  a 
sulphuret  of  lead;  filter,  dry,  and  weigh.  16.1 
parts  will  be  sulphur,  and  103.6  parts  lead,  -fa 
part  of  the  weight  of  the  sulphur,  added  to  its 
weight,  will  give  the  weight  of  the  hydrosulphu- 
ric acid 

If  the  water,  after  being  boiled,  yields  a  black 

precipitate,  with  acetate  of  lead,  acetic  acid  must  be  added,  and  the 
liquor  boiled,  and  the  gas  passed  through  the  acetate,  as  before. 

The  mode  of  estimating  the  solid  matter  held  in  solution  in  mineral 
waters  is  simply  to  boil  the  whole  to  dryness,  and  weigh  the  residue. 
The  different  kinds  of  matter  are  then  detected  in  the  usual  way  for 
analyzing  other  solid  bodies. 


Fig.  104, 


Test  Tubes.  For 
the  purpose  of  test- 
ing substances  in 
solution,  test  tubes 
(Fig.  105)  are  very 
convenient.  They 
are  glass  tubes, from 
3  to  12  inches  in 
length,  and  from  J 
to  1  inch  in  diame- 
ter, open  at  one  end, 
while  the  closed  end 
is  so  made  that  the 
liquid  may  be  heat- 

ii 


Fig.   105. 


30-2 


Analytical  Chemistry. 


ed  as  in  a  retort.  A  small  quantity  of  any  solution  may  be 
examined  in  them  with  great  facility,  and  they  are  especially 
convenient  to  form  precipitates.  These  tubes  may  be  placed 
upon  a  frame,  as  in  the  figure,  and  answer  often  the  threefold 
purpose  of  retort,  receiver,  and  test  tube. 

Filtration.  When  a  solution  has  been  prepared  for  exam- 
ination, it  ought  to  be  perfectly  clear.  If  it  appears  muddy, 
it  must  be  subjected  to  filtration  ;  that  is,  it  must  be  passed 
through  a  paper  filter,  by  which  means  it  is  separated  from 
solid  matters,  which  make  it  appear  opaque.  As  this  oj>< -ra- 
tion frequently  occurs  in  chemical  analysis,  and  in  ni 
manipulations,  it  is  important  to  understand  the  mode  of  per- 
forming it. 

The  filtering  paper  should  contain  no  glazing  or  sizing, 
and  should  be  folded  in  the  following  form :  — 

1.  Take  a  square  piece  of  paper,  and  fold  it  like  a  sheet  of 
paper,  that  is,  so  as  to  bring  two  corners  together ;  then  fold 
it  so  as  to  bring  four  corners  together;  cut  off  the  corner-. 
and  by  opening  the  folds  it  will  have  the  form  of  an  inverted 
cone,  and  may  be  placed  in  a  funnel. 


2.  But  for  filtering  rapidly, 
the  filter  may  be  folded  in  the 
following  form  :  —  Fold  the  pa- 
per in  two,  as  before  ;  then  (Fig. 
106)  fold  10  upon  2,  then  10 
upon  6,  then  1  10  upon  1  8, 
then  2  upon  8,  then  2  upon  6, 
2  upon  4,  and  10  upon  4 :  this  will  produce 
7  folds,  all  on  one  side  of  the  pnper.  Slake, 
now,  folds  between  each  of  these,  so  as  to 
raise  ribs  on  the  opposite  side  of  the  paper. 
Cut  out  the  projecting  corners,  to  give  the 
whole  acircularshape  ;  open  it,  and  form  it  into 
a  cup.  (Fig.  107.) 


100. 


107. 


Filtration, 


363 


Fig.  108. 


The  filter  may  then  be  placed 
in  the  funnel  c,  (Fig.  108,)  and 
supported  by  a  lamp-stand  or  a 
wood-stand,  made  for  the  pur- 
pose ;  or  it  may  be  placed  in  the 
top  of  a  tall  jar.  The  liquid  to 
be  filtered  is  then  put  into  it,  and 
a  vessel  placed  beneath  to  con- 
tain the  liquid  as  it  slowly  passes 
through  the  paper.  By  this  pro- 
cess, the  solid  and  liquid  parts 
are  separated,  and  either  may 
be  examined  in  their  separate 
st  ;lr.:< 

If  it  is  desired  to  estimate  the  quantity  of  solid  matter,  the 
filter  must  be  weighed  previous  to  placing  it  in  the  funnel ; 
and  the  solid  matter,  after  being  washed,  by  directing  a  fine 
stream  of  water  upon  it,  until  the  water  comes  through  taste- 
less, is  dried  and  weighed :  the  difference  of  weight  shows 
the  quantity  of  solid  matter. 

Supports  of  filters  and  vessels  may  be 
of  iron  wire,  made  into  the  form  of  a  tri- 
angle. (Fig.  109.)  Take  three  pieces  of 
iron  or  copper  wire,  and  twist  the  ends  as 
in  the  figure,  leaving  a  triangular  aperture  : 
this  may  be  placed  upon  the  tops  of  jars 
and  other  vessels,  or  upon  the  rings  of  the 
lamp -stand,  to  support  crucibles,  evapo- 
rating dishes,  retort*;,  filters,  &,c. 


Fig.  109. 


*  For  clicmicni   manipulation,  and  blowpipe  analysis,  the  student  is 
referred  to  Griffin's  Chemical  Recieations. 


APPENDIX 


Wollaston's  Synoptic  Scale  of  Chemical  Equivalent*.*  — 
The   scale  consists  of  a  movable   slider,  with  a  seri< 
numbers  upon  it,  from  10  to  320,  on  each  side  of  whicli 
on  the  fixed  part  of  the  scale,  are  set  down  the  names  of  va- 
rious chemical  substances. 

The  scale  is  founded  on  the  constancy  of  composition  in 
chemical  compounds,  the  equivalent  power  of  the  quantities 
that  enter  into  combinations,  and  the  properties  of  a  logo* 
metric  scale  of  numbers. 

The  numbers  are  so  arranged,  that  at  equal  intervals  they 
bear  the  same  proportion  to  each  other.  The  student  \\  ill 
easily  observe  and  understand  this,  by  measuring  a  feu  dis- 
tances upon  the  scale,  with  a  pair  of  compasses,  or  even  a 
piece  of  paper.  If  his  paper  extend  from  10  to  20,  it  will 
also  extend  from  20  to  40,  or  from  55  to  110,  or  from  100  to 
320.  Whatever  number  is  at  the  upper  edge  of  the  paper 
will  be  double  at  the  lower.  If  any  other  distance  l>r  taken, 
the  same  effect  will  be  observed.  If,  for  instance,  the  paper 
extends  from  10  to  14,  then  any  other  two  numbers  found  at 
its  upper  and  lower  edge  will  be  in  the  same  proportion  as 
these  two  numbers  10  and  14.  Thus,  make  the  upper  num- 
ber 100,  and  the  lower  number  will  be  140. ' 

Now,  supposing  that  the  paper  were  cut  of  such  a  width 
that,  one  of  its  edges  being  applied  upon  the  scale  to  the  num- 
ber representing  the  equivalent  of  one  body,  the  other  should 
coincide  with  the  number  of  the  equivalent  of  a*  second  body ; 
then,  upon  moving  the  paper,  wherever  it  was  placed  over  the 
numbers,  those  at  its  upper  and  lower  edges  would  still  rep- 
resent the  corresponding  proportional  quantities  of  the  two 
bodies  as  accurately  as  at  first,  because  the  numbers  at  equal 

*  The  paper,  by  iU  author,  describing  the  scale,  is  inserted  in  the 
Philosophical  Transactions  for  1814. 


Appendix.  365 

distances  on  the  scale  are  proportional  to  each  other.  Thus, 
suppose  the  upper  edge  were  made  to  coincide  with  40  and 
the  lower  with  78,  then  the  upper  edge  might  be  called  sul- 
phuric acid,  and  the  lower  baryta;  and  this  width  once  as- 
certained, the  paper,  wherever  applied  upon  the  scale,  would 
show  at  its  lower  edge  the  quantity  of  baryta  necessary  to 
combine  with  the  quantity  of  sulphuric  acid  indicated  by  its 
upper  edge. ' 

It  is  evidently  of  no  consequence  whether  the  paper  be 
moved  up  and  down  over  the  scale,  or  the  line  of  numbers 
be  moved  higher  and  lower,  to  bring  its  different  parts  to  the 
edges  of  the  paper.  And  supposing  the  piece  of  paper  just 
described  to  be  pasted  upon  the  side  of  the  scale,  then,  by 
moving  the  latter,  any  of  the  numbers  might  be  made  to  coin- 
cide with  the  upper  or  lower  edge  at  pleasure,  and  conse- 
quently the  quantity  of  sulphuric  acid  necessary  to  combine 
with  any  quantity  of  baryta,  and  vice  versa,  ascertained  by 
mere  adjustment  and  inspection  of  the  scale.  Or  if,  instead 
of  referring  to  the  separate  piece  of  pap'er,  marks  were  to  be 
made  on  the  side  of  the  scale  at  40  and  78,  and  named  sul- 
phuric acid  and-  baryta,  the  same  object  would  be  attained, 
and  the  same  method  of  inquiry  rendered  available. 

Other  substances  are  to  be  put  down  upon  the  scale  ex- 
actly in  the  same  manner.  Thus,  the  scale  being  adjusted 
until  the  number  40  coincides  with  the  sulphuric  acid  already 
marked,  then  sulphate  of  baryta  is  to  be  written  at  118,  and 
thus  its  place  is  ascertained ;  nitrate  of  baryta  at  132  ;  soda 
at  •{-  ;  sulphate  of  soda  at  72 ;  and  a  similar  process  is  to  be 
adopted  with  every  substance,  the  number  of  which  has  been 
ascertained  by  experiment.  The  instrument,  which  in  this 
state  merely  represents  the  actual  numbers  supplied  by  exper- 
iment, will  faithfully  preserve  the  proportions  thus  set  down, 
whatever  the  variation  of  the  position  of  the  slider  may  be. 
It  is  therefore  competent  to  change  all  the  numerical  expres- 
sions to  any  degree  required,  the  knowledge  of  one  only  being 
sufficient,  first  by  adjustment,  and  then  by  inspection,  to  lead 
to  the  rest. 

A  few  illustrations  of  the  powers  and  uses  of  this  scale 
will  be  sufficient  to  make  the  student  perfect  master  of  its 
nature  and  applications.  Suppose  that,  in  analyzing  a  mineral 
water,  the  sulphates  in  a  pint  of  it  have  been  decomposed  by 
the  addition  of  muriate  of  baryta,  and  the  resulting  sulphate 
of  baryta  washed,  dried,  and  weighed ;  from  its  quantity  may 
31* 


366  Appendix. 

be  deduced  the  exact  quantity  of  sulphuric  acid  previously 
existing  in  the  mineral  water.  Thus,  if  the  sulphate  of  baryta 
amount  to  43.4  grains,  the  slider  is  to  be  moved  until  that 
number  is  opposite  to  the  sulphate  of  baryta,  and  then  at  sul- 
phuric acid  will  be  found  the  quantity  required,  namely,  14.7 
grains.  In  the  same  manner  the  scale  will  give  information 
of  the  quantity  of  any  substance  contained  in  a  gi\  en  weight  of 
any  of  its  compounds;  these  having  previously  been  deduced 
from  experiment,  and  accurately  set  down  on  the  table  in  the 
manner  just  explained. 

If  it  be  desired  to  know  how  much  of  one  substance  must 
be  used  in  an  experiment  to  act  upon  the  other,  it  is  evident 
that  the  equivalent  must  be  taken,  and  this  may  be  learned 
from  the  scale.     Suppose  that  a  pound  of  sulphate  of  harm 
has  been  mixed  with  charcoal,  and  well  heated,  to  convert  it 
into  a  sulphuret,  and  that  by  the  addition  <>i   nitric  aci<! 
to  be  converted  into  nitrate  of  baryta.     Tin-  quantity  o! 
which  will  probably  be  required  may  be  learned  by  l»rii 
100  to  sulphate  of  baryta,  and  then  by  looking  for  the  num- 
ber opposite  nitric  acid  ;  it  will  be  found  to  be  40.     But  this 
represents  the  quantity  of  dry  acid  ;  casting  the  eye  ther 
lower  down,  upon  liquid  nitric  acid  of  a  specific  gravity  o{' 
1.50,  it  will   be  found  that  61  Ibs.,  or  a  little  more,  is  the 
equivalent  for  100  Ibs.,  and  consequently  thnt  <>1    hundredth 
pans,  or  somewhat  above  fa  of  a  pound  of  six -h   acid,  \vi!l 
be  sufficient  for  the  pound  of  sulphate  of  baryta   operated 
with. 

If  a  certain  weight  of  carbonate  of  baryta  be  required  in 
that  moist  and  finely-divided  state  in  which  it  is  obtained  by 
precipitation,  and  in  which  it  cannot  be  weighed,  the 
racy  of  the  quantity  may  be  insured  by  taking  the  equivalent 
of  dry  muriate,  or  nitrate  of  baryta,  precip  !»v  an  ex- 

cess of  carbonate  of  potassa,  and  then  washing  off  the 
which  remain  in  solution.  Suppose  100  grains  of  the  car- 
bonate were  required;  by  Bringing  that  number  to  carbonate 
of  baryta,  it  will  be  found  tint  the  quantity  of  dry  muriate 
necessary  will  be  105.8  parts,  and  Ae  quantity  of  nitrate 
133.4  ;  and  if  the  quantity  of  carbonate  of  potassa  necessary 
for  this  purpose  be  also  required,  it  will  be  found,  opposite 
the  name  of  that  substance  on  the  scale,  to  be  a  little  less 
than  70  parts,  so  that  5  or  10  parts  more  will  insure  a  satis- 
factory excess. 

The  second  paragraph  of  Wollaston's  description  of  this 


Appendix.  367 

scale  may  be  transcribed,  as  a  further  illustration  of  the 
powers  of  the  instrument.  "  If,  for  instance,  the  salt  under 
examination  be  the  common  blue  vitriol,  or  crystallized  sul- 
phate of  copper,  the  first  obvious  questions  are  —  (1)  How 
much  sulphuric  acid  does  it  contain  ?  (2)  How  much  oxide 
of  copper?  (3)  How  much  water  ?  He  [the  analytic  chemist] 
may  not  be  satisfied  with  these  first  steps  in  the  analysis,  but 
may  dosire  to  know  further  the  quantities  (4)  of  sulphur,  (5) 
of  copper,  (6)  ofv  oxygen,  (7)  of  hydrogen.  As  means  of 
nr-uiiiiKT  this  information,  he  naturally  considers  the  quantity 
of  various  re-agents  that  may  be  employed  for  discovering  the 
quantity  of  sulphuric  acid,  (8)  how  much  baryta,  (9)  carbon- 
ate of  baryta,  or  (10)  nitrate  cf  baryta,  would  be  requisite 
for  this  purpose.  ( J 1 )  How  much  lead  is  to  be  used  in  the 
form  of  (12)  nitrnte  of  lead;  and  when  the  precipitate  of 
(13)  sulphate  of  baryta,  or  (14)  sulphate  of  lead,  are  obtained, 
it  will  be  necessary  that  he  should  also  know  the  proportion 
which  either  of  them  contains  of  dry  sulphuric  acid.  He 
nny  also  endeavor  to  ascertain  the  same  point  by  means  of 
(15)  the  quantity  of  pure  potassa,  or  (10)  of  carbonate  of 
pot  i-s  i,  requisite  for  the  precipitation  of  the  copper.  He 
rnitrht  also  use  (17)  zinc,  or  (18)  iron,  for  the  same  purpose; 
and  he  may  wish  to  know  the  quantities  of  (19)  sulphate  of 
zinc,  or  (20)  sulphate  of  iron,  that  will  then  remain  in  the 
solution." 

All  these  questions  and  points  are  answered  by  moving  the 
slider  until  the  number  expressing  the  quantity  operated  with, 
coincides  with  sulphate  of  copper  crystallized.  5,  Water. 
Let  it,  for  instance,  be  100;  this  being  brought  opposite  crys- 
tallized sulphate  of  copper,  the  information  relative  to  all  the 
above  points,  except  the  sixth  and  seventh,  is  supplied  by 
mere  inspection.  The  sixth  may  be  supplied  by  subtracting 
(5)  the  quantity  of  copper  from  (2)  the  quantity  of  oxide  of 
copper,  or  by  halving  the  quantity  at  2  oxygen,  or  taking  the 
third  of  that  at  3  oxygen.  The  seventh  relates  to  the  quan- 
tity of  hydrogen  in  the  5  water  present  in  the  salt;  this  quan- 
tity of  hydrogen  does  not  come  within  the  line  of  numbers, 
but  may  easily  be  obtained  by  doubling  the  quantity  of  water, 
or  doubling  the  quantity  of  the  salt  used,  which  will  then 
bring  10  hydrogen  into  the  scale,  and  the  half  of  this  is  to  be 
taken  as  the  quantity  in  5  water,  or  in  100  grains  of  the  salt. 
Putting,  therefore,  200  to  sulphate  of  copper,  10  hydrogen,  is 
indicated  as  17  parts  nearly,  when  of  course  the  half  of  this, 


368  -  Appendix. 

or  8.5  parts,  is  the  quantity  in  100  grains  of  the  crystallized 
salt  of  copper. 

Whenever  it  thus  happens  that  the  number  known  or  the 
number  sought  for  is  out  of  the  scale,  then  some  convenient 
multiplier  of  the  numbers  may  be  used.  The  most  conve- 
nient method  is  to  use  the  tens  or  the  hundreds  as  units.  <>r, 
what  is  the  same  thing,  to  consider  for  the  time  that  dt< 
points  are  inserted  between  the  units  and  the  tens,  or  bet 
the  tens  and  the  hundreds  of  all  the  numbers  on  the  scale. 
Thus,  if  it  were  required  to  ascertain  how  much  magnesia  and 
sulphuric  acid  were  contained  in  a  pound  of  crystallized  sul- 
plnte  of  magnesia,  no  1  exists  upon  the  scale,  and  of  course 
no  fractions  or  small  parts  of  1  ;  but  imagine  decimal  points 
hetween'the  tens  and  the  hundreds,  then  10  upon  the 
becomes  one  tenth,  22  twenty-two  hundredth*,  108  one,  220 
two  and  two  tenths,  and  so  on.  Bringing,  therefore,  100  to 
crystallized  sulphate  of  magnesia,  it  represents  the  1  pound, 
;m<l  by  inspection  it  will  "be  found  that  it  contains  16  hun- 
dredths  of  a  pound  of  magnesia,  and  32J  hundreds  of  a  pound 
of  sulphuric  acid. 

As  another  illustration,  suppose  that  the  quantity  of  mag- 
nesia in  50  Ibs.  of  crystallized  Epsom  salt  were  requin-.] ; 
upon  bringing  50  opposite  the  name  of  the  salt,  the  quantity 
of  magnesia  will  be  found  smaller  than  any  quantity  expressed 
upon  the  scale ;  but  all  that  is  necessary  to  obtain  the  answer 
is,  to  double  the  quantity  of  the  salt,  and  then  to  halve  the 
quantity  of  magnesia  indicated  ;  in  which  way  it  will  be  found 
that  the  50  Ibs.  contain  about  8  Ibs.  of  the  oxide. 

These  Synoptic  Scales  are  generally  constructed  of  paper 
or  wood.  It  is  almost  impossible  that  they  should  be  accu- 
rate, because  of  the  extension  and  contraction  of  the  paper, 
and  the  facility  with  which  it  yields  to  mechanical  impressions, 
and  may  be  stretched  when  in  a  moistened  state.  These  scales 
should  never  be  considered  as  accurate  when  they  first  come 
from  the  instrument-maker.  They  may  be  examined  by  a 
pair  of  compasses  or  a  piece  of  paper,  to  ascertain  how  nearly 
equal  intervals  on  the  scale  of  numbers  accord  with  equal 
proportions  between  the  numbers  at  the  extremities  of  those 
intervals,  and  thus  the  degree  of  error  in  them,  and  the  part 
where  it  exists  to  the  greatest  extent,  may  be  observed;  but  it 
will  be  useless  to  do  so  with  the  view  of  finding  one  so  accu- 
rate as  to  dispense  with  calculation  in  exact  analytical  exper- 
iment. 


Appendix.  369 

Those  scales  which  are  laid  down  directly  upon  wood, 
though  not  liable  to  the  same  sources  of  error  as  the  paper 
scales,  are  still  seldom,  if  ever,  so  accurate  as  to  compete 
with  calculation.  —  W. 

Cementing.  1.  When  vapors  of  watery  liquors,  and  such 
others  as  are  not  corrosive,  are  to  be  confined,  it  is  sufficient 
to  surround  the  joining  of  the  receiver  to  the  retort  with 
slips  of  wet  bl-idder,  or  of  linen,  or  paper,  covered  with  flour 
paste,  or  mucilage  of  gum  arabic. 

2.  Soft  cement  is  made  of  yellow  wax  melted  with  half  its 
weight  of  turpentine  and  a  little  Venetian  red  to  give  it  color. 
It  can   be  eisily  moulded  by  the  fingers,  and  sticks  well  to 
dry  substances. 

3.  For  containing  the  vapors  of  acid,  or  highly-corrosive 
substances,  fat  lute  is  made  use  of.     This  is  formed  by  beat- 
ing perfectly  dry  and   finely-sifted  tobacco-pipe  clay,    with 
painters'  drying  oil,  in  a  mortar,  to  such  a  consistence  that  it 
may  be  moulded  by  the  hand.     To  use  it,  it  is  rolled  into 
cylinders  of  a  convenient  size,  which  are  applied,  by  flatten- 
ing them,  to  the  joinings  of  the  vessels,  which  must  be  quite 
dry,  as  the  least  moisture  prevents  the  lute  from. adhering. 
The  lute,  when  applied,  is  to  be  covered  with  slips  of  linen 
spread  with  the  lime  lute ;    which  slips  are  to  be  fastened 
with  pack-thread. 

4.  When  penetrating  and  dissolving  vapors  are  to  be  con- 
fined, the  lute  to  be  employed  is  of  quick  lime  slacked  in  the 
air,  and  "beaten  into  a  liquid  paste  with  white  of  eggs.     This 
must  be  applied  on  strips  of  linen  ;  it  is  very  convenient,  as 
it  erisily  dries,  and  becomes  firm.     This  lute  is  very  useful 
for  joining  broken  chinq  ware. 

5.  For  cementing  stone  ware  to  metals  and  wood,  litharge 
and  red  lead  mixed  and. worked  up  with  spirit  of  turpentine, 
makes  a  good  cement.     It  takes  several  days  to  give  off  the 
turpentine  and  become  dry  and  hard. 

6.  Cement  for  fastening  brass  necks  upon  glass  jars,  etc.  : 
—  4  parts  of  rosin,  1  of  wax,  and  1  of  finely-powdered  brick 
are  melted  and  well  mixed  together.     It  is  to  be  put  on  warm, 
but  care  is  to  be  taken  not  to  apply  it  so  hot  as  to  split  the 
glass.     It  holds  very  hard. 

7.  Mix  linseed  meal  with  water,   and  knead  it  into  a  stiff 
paste.     It  soon  hardens,  and  withstands  the  fumes  of  acids 
and  ammonia.     It  is  better  if  made  with  lime  water,  or  thin 
glue.     It  is  charred  by  a  strong  heat. 


370  Appendix. 

8.  Thick  gum  water,  with  pipe  clay  and  iron-filings.    Mix 
well.      It  becomes  very  hard  and  firm,  and   is  fit  to  be 
where  it  is  required  to  hold  good  a  considerable  time. 

9.  Plaster  of  Paris,  stirred  up  with  milk,  starch  water,  or 
thin  glue.     It  hardens  immediately,   and    is  very  good  for 
securing  tubes  in  flasks,  when  the  corks  do  not  fit  \\ell,  and 
gases  are  to  be  prepared  in  them. 

10.  Dissolve  melted  India  rubber  in  boiling  linseed  oil, 
and  afterwards  thicken  the  latter  with  pipe  clay  till  it  forms 
a  stiff  mass.     The  thorough  incorporation  of  the  pipe  clay 
demands  a  great  deal  of  labor.     This  is  a  capital  cement  to 
be  used  when  acids  are  to  be  prepared. 

11.  Cement  for  fastening  Labels  upon  Bottles.    Soften  a  ml 
subsequently  boil  glue  in  strong  yinegar.     During  the  boil- 
ing, thicken  it  with  flour.     This  mixture  can  bo  pre.-rm-d  in 
a  soft  state  without  becoming  mouldy.     It  should  be  put  into 
a  glass  bottle,  with  a  wide  neck  and  a  ground  stopper.     \V  lu-n 
it  is  to  be  used,  it  is  taken  out  of  the  bottle  on  the  point  of  a 
spatula,  warmed  over  the  lamp,  if  too  thick  for  use,  and  then 
spread  upon  the  paper. 

12.  Universal  dement.     Curdle  skim  milk,  press  out  the 
whey,  break  the  curd  in  small  pieces,  dry  it,  and  grind  it  in  a 
coffee  mill.     Take  ten  ounces  of  dry  curd,  one  ounce  of  ire>h 
burnt  quicklime,   and  two  scruples  of  camphor.     Mix   tin- 
whole  intimately,  and  preserve   it  in   small,  wide-mouthed 
bottles,  closely  corked.  •  When  it  is  to  be  used,  mix  it  with 
a  little  water,  and  apply  it  immediately. 

Irt.  Diamond  Cement  for  Glass  or  Porcelain.  Dis.-<!\r 
five  or  six  pieces  of  gum  mastic,  as  large  as  peas,  in  the 
smallest  possible  quantity  of  alcohol.  Mix  this  liquid  with 
two  ounces  of  a  stron-j  solution  of  isinula-s  (made  by  soften- 
ing and  dissolving  isinglass  in  boiling  brandy  or  rum  to 
saturation.)  having  previously  incorporated  the  two  ounces 
of  isinglass  solution  with  two  or  three  small  pieces  of  galba- 
num  or  gum  ammoniac,  by  trituration.  -  The  mixture  is  to  be 
preserved  in  a  well-closed  bottle,  and  is  to  be  gently  1. 
by  holding  the  bottle  in  hot  water  at  the  moment  when  yog 
are  goinglto  use  it.  —  Griffin's  Chem.  Recreations. 


Eli  stir.  Tube  Miking.  Take  a  piece  of  the  sheet  rubber,  1  or  1£ 
inches  long,  and  a  little  more  than  three  times  as  wide  as  you  intend 
the  tube  to  be.  Take  a  glass  rod  rather  smaller  than  the  intended 


Appendix.  37 1 

caoutchouc  tube,  fold  a  slip  of  paper  round  the  glass  rod,  and  over  it 
the  piece  of  caoutchouc,  previously  softened  by  wanning  before  the 
fire.  Fold  the  two  edges  together,  and  cut  off  the  double  projecting 
edges  by  a  pair  of  scissors,  so  as  to  produce  two  parallel  straight  edges. 
Put  the  two  clean  surfaces  thus  produced  face  to  face,  being  careful  not 
to  let  the  fingers,  or  any  thing  else,  touch  them.  Press  the  two  faces 
together  by  the  thumb  nails,  and  finally  press  the  seam  from  end  to 
end  with  the  flat  part  of  the  thumb  nail.  The  junction  is  then  effected 
and  the  tube  complete.  But  if  the  fingers  or  any  dirt  is  allowed  to 
touch  the  clean  cut  surfaces  of  the  rubber,  they  cannot  be  made  to 
unite  by  pressure.  After  you  have  withdrawn  the  glass"  rod  and  the 
slip  of  paper  from  the  rubber  tube,  you  are  to  smear  its  inner  surface 
with  flour  or  fine  ashes,  to  prevent  the  subsequent  sticking  together  of 
its  sides,  which  is  otherwise  liable  to  take  place.  — Ib. 


Cutting  Glass.  Dissolve  in  spirits  of  turpentine  as  much  camphor 
gum  as  the  liquid  will  hold  in  solution  by  the  aid  of  moderate  heat  —  a 
common  file  dipped  into  the  solution  and  applied  to  glass,  will  cut  it 
with  nearly  the  same  facility  as  iron. 


Specific  Gravity  of  Essential  and  other  Oils. 

Oil  of  Anise-seed,          .         .      , 0.9958 

Bergainot,  .         .         .        .J  .         .         .        .  0.885 

Cajeput,      .         ..,",,'.         .:       .         .         .      .  .         .  0.948 

Caraway,    .         .:''    .         ., 0.975 

Cassia,         .         .*-»•-;        .} 1.071 

Cinnamon,  ,1J&  .      ,   .* 1.035 

Cloves,        .  1.061 

Fennel,        .      .".'/.*•    .•  0.997 

Juniper, 0.911 

'    Lavender,    .         .'-     .        .'        ,V.  .  •*-.'-;..         .  0.898 

Lemons,      .         «*'/.-^  ""'•    //;"    ... .--;'    .         .         .  0.8517 

Nutmegs,    .       V.      ^:  *  .-      ,--.\y»   j    •  •.-•••'      -  0.948 

Peppermint, 0.899 

Roses,  (Ottar  of  Roses,)      .         .  .         .         .  0.832 

Rosemary,  0.85 

Oils  of  Fermented  Liquors. 

Oil  of  Grain  Spirits,     .        ,  -^  * 0.835 

"    "    Potato  Spirits,     .         .  -  /  7- 0.821 


372 


Appendix. 


TABLE. 

The  following  are  the  results  obtained  by  a  commission  ap- 
pointed by  the  Parisian  Academy  of  Sciences  to  ciuinint' 
the  elastic  force  of  vapor.*  They  were  obtained  by 
experiment  up  to  a  pressure  of  25  atmospheres ,  <nul  at 
higher  pressures  by  calculation. 


Elajticityofihe  van. 
taking  utmocpiicric 
preu.  u  unity. 

Ti  m[M>rature  Re- 
cording to  Fahr. 

Ulantirity  uf  the  vap. 
taking  atmospheric 
preac.  as  unitj. 

;>erntur«  ac- 
cording to  Fahr. 

1 

212° 

13 

380.66° 

u 

233.96    ' 

14 

386.94 

2 

250..VJ 

15 

392.86 

2} 

263.84 

16 

898.48 

3 

275.18 

17 

403.82 

3J 

285.08 

18 

408.92 

4 

293.72 

19 

4i:*/> 

ft 

300.28 

20 

418.46 

5* 

307.5 

21 

422.96* 

5J 

314.24 

22 

427.28 

6 

320.36 

23 

l:*1.42 

6} 

-826.26 

24 

l:r>r,(; 

7 

331.70 

25 

480*34 

7J 

336.86 

30 

457.14 

8 

341.78 

35 

47*78 

9 

350.78 

40 

480..",!) 

10 

358.88 

45 

491.1  I 

11 

366.85 

50 

510.00 

12 

374.00 

*  Brande'i  Jour.  N.  S.  viii.  191. 


GLOSSARY. 


A. 

ABSORPTION,  from  absorbeo,  to  suck  up;  the  power  or  act  of  imbibing 

a  fluid. 

ACETIC  ACID,  from  acetum,  vinegar;  the  acidifying  principle  of  com- 
mon vinegar. 

ACICULAR,  from  acus,  a  needle ;  having  sharp  points  like  needles. 
ACTION,  from  uyu>,  to  move ;  the  effort  by  which  one  body  produces, 

or  endeavors  to  produce,  motion  in  another. 
ADHESION,  -IVE,  from  ad,  to,  and  htereo,  to  stick;  the  tendency  which 

dissimilar  bodies  have  to  adhere  or  stick  together. 
AERATION,  from  <*/,£,  the  air;  the  saturation  of  a  liquid  with  air. 
AERIFORM,  from  aer,  the  air,  and  forma,  a  form;    having  the   forr.i 

of  air. 
AEROSTATION,  from  <*/,(>,  the  air,  and  'ianjui,  to  weigh;  primarily,  it 

denotes  the  science  of  weights  suspended  in  the  air;  but,  in  the 

modern  application  of  the  term,  it  signifies  the  art  of  navigating 

the  air. 
AFFINITY,  from  ad,  to,  and  finis,  a  boundary;  relationship;  the  force 

which  causes  dissimilar  particles  of  matter  to  combine  together, 

so  as  to  form  new  matter. 
ALBUMEN, -INOUS,  from  albumen,  the  white  of  an  egg;  an  important 

animal  principle.     The  white  of  an  egg  is  albumen  mixed  with 

water. 
ALKALI,  a  soluble  body,  with  a  hot,  caustic  taste,  which  possesses  the 

power  of  destroying  acidity ;  the  term  is  derived  from  kali,  the 

Arabic  name  of  a  plant,  from  the  ashes  of  which  one  species  is 

obtained,  and  the  article  al. 
AMALGAM,  from  aua,  together,  and  yaut'co,  to  marry  ;  a  chemical  term, 

signifying  the  union  of  any  metal  with  mercury,  which  is  a  sol- 
vent of  various  metals. 

AMORPHOUS,  from  a,  not,  and  /<oo</n' \,  a  form ;  not  possessing  regular  form. 
ANALYSIS,  from  aru,  thoroughly,  and  J.vvi,  to  loosen;  the, separation  of 

a  whole  into  parts. 
ANGLE,  from  angulus,  a  corner;  the  inclination  of  two  straight  lines 

to  each  other,  which   meet  together,  but  are  not  in  the  same 

straight  line. 

ANHYDROUS,  from  «,  not,  and  vdwn,  water;  containing  no  water. 
ASION,  from  av'u,  up,  and  sfytt,  to  go;  that  which  goes  up;  a  substance 

which  in  electrolysis  passes  to  the  anode. 
ANODE,  from  am,  up,  and  6f?6?,  a  way;  the  way  which  the  sun  rises; 

the  surface  at  which  the  electricity  passes  into  a  body,  supposing 

the  currents  to  move  in  the  apparent  direction  of  the  sun. 
ANTISEPTIC,  from  avri,  against,  and  a>tnw,  to  make  rotten;  possessing 

the  power  of  preventing  putrefaction. 

32 


374  Glossary. 

APPROXIMATE,  -IVELY,  from  ad,  to,  and  proximus,  nearest;   having 

affinity  with  ;  bordering  upon. 
AQUA  REGIA,  i.e.,  REGAL  WATER,  a  mixture  of  nitric  and  muriatic 

acids;  so  called  from  its  property  of  dissolving  gold,  held  by  the 

alchemists  to  be  the  king  of  the  metals. 
Aftufco,  from   aqua,  water;    when  prefixed  to  a  word,  denotes  that 

water  enters   into   the   composition   of  the   substance    which   it 

signifies. 
ARC,  from   arcus,  a  bow;   a  part  of  a  curved  line,  as  of  a  circle, 

ellipse,  &e. 
ARMATURE,  from  armo,  to  arm  ;  a  piece  of  soft  iron  applied  to  a  load- 

stone, or  connecting  the  poles  of  a  horseshoe  magnet. 
ASTATIC  NEEDLE,  from  U<UUTOC,  balanced;  a  double  magnetic  needle, 

not  affected  by  the  earth's  magneti 
ASTRONOMY,  from  unroot,  a  star,  and  t.'i/«-,  a  law  or  rule;  the  science 

which  treats  of  the  heavenly  bodies,  their  motions,  periods,  &c., 

and  the  causes  on  which  they  depend. 
ATHERMANOUS,  from  a,  not,  and  £»Viiu;,  heat;   that  through  whirh 

heat  will  not  pass  is  said  to  be  -atliennanous. 
ATMOSPHERE,  -it,  from  Cftpiiy,  vapor,  and  o</ui\»u,  a  sphere;  the  sphere 

of  air  which  surrounds  the  globe. 
ATOM,  -ic,  from  a,  not,  and  rii<io<,  to  cut;  a  minute  particle,  not  sus- 

ceptible of  further  division. 
ATTRACTION,  -IVE,  from  ad,  to,  and  traho,  to  draw;  the  tendency  which 

bodies  have  to  approach  each  other. 
AUSTRAL,  from  austrr,  the  south  ;  southern. 
Axis,  in  geometry  ;  the  straight  line  in  a  plane  figure,  about  which  it 

revolves  to  produce  or  generate  a  solid;  more  generally,  the  right 

line  conceived  to  be  drawn  from  the  vertex  of  a  figure  to  the 

middle  of  the  base. 

B. 


BAROMETER,  -RICAL,  from  ^ugoc,  weight,  and  ^«'r(>o*,  a  measure;  an 
instrument  for  measuring  the  varying  weight  of  the  atinospln-  n- 

BIBULOUS,  from  6160,  to  drink;  that  which  has  the  quality  of  drinking 
in  moisture. 

BINARY,  from  big,  twice  ;  containing  two  units. 

BOREAL,  from  boreas,  the  north  ;  northern. 

C. 

CALORIMETER,  from  color,  heat,  and  mrtrvm,  a  measure  ;  an  instnun.  nt 

for  measuring  caloric. 
CAPILLARY,  from  capillus,  a  hair;  resembling  or  having  the   form 

of  hairs. 

CAPSULE,  from  rapsiila,  a  little  chest;  a  small,  shallow  cup. 
CARBON,  from  carbo,  a  coal  ;  the  chemical  name  for  charcoal. 
CATALYSIS,  from  xaru,  thoroughly,  and  irw,  to  loosen;  an  imaginary 

force,  Which  is  supposed  to  assist  the  decomposition  of  some  bodies, 

and  the  composition  of  others. 
CATHODE,  from  xaru,  downward,  and  o<Joc,  a  way;  the  way  which  the 

sun  sets  ;  the  surface  at  which  electricity  passes  out  of  a  body, 

supposing  the  current  to  move  in  the  apparent  direction  of  the  sun. 
CATION,  from  xora,  down,  and  iun,  to  go;  that  which  goes  down;  a 

substance  which  in  electrolysis  passes  to  the  cathode. 
CAUSTIC,  from  xatcu,  to  burn  ;  possessing  the  power  of  burning. 


Glossary.  375 

CHEMISTRY,  -ICAL,  from  an  Arabic  word,  signifying  the  knowledge  of 

the  substance  or  constitution  of  bodies;  the  science  whose  object 

it  is  to  examine  the  constitution  of  bodies. 
CIRCUMFERENCE, -TIAL,  from  circum,  around,  and /ero,  to  bear;  the 

line  which  is  the  boundary  of  a  circle. 
CLEAVAGE,  PLANE  OF  ;  the  plane  in  which  crystals  have  a  tendency  to 

separate. 
COHESION,  -rvE,  from  con,  together,  and  hccreo,  lo  stick ;  the  relation 

among   the   component   parts   of  a  body,   by   which   they  cling 

together. 
COMBUSTION,  from  comburo,  to  burn;  the  disengagement  of  light  and 

heat  which  accompanies  chemical  combination. 
CONCAVE,  from  concavus,  hollow  ;  curved  inwardly,  or  hollow. 
CONDUCTION,  from  con,  together,  and  duco,  to  lead.     The  power  of 

transmitting  caloric,  without  change  in  the  relative  position  of  the' 

particles  of  the  conducting  body. 
CONE,  -ICAL,  and  -ic ;  a  solid  "figure,  having  a  circular  base,  and  its 

other  extremity  or  vertex  terminated  by  a  point. 
CONGELATION,  from  con,  together,  and  gdo,  to  freeze ;  the  process  of 

freezing. 
CONGERIES,  from   congeries,  a  heap;   a  mass   of  bodies   heaped   up 

together. 
CONSTITUENT,  from  constituo,  to  put  together;  that  of  which  any  thing 

consists  or  is  made  up. 
CONTACT,  from  con,  together,  and  tango,  to  touch ;  the  relative  state 

of  two  things  which  touch  one  another,  but  do  not  cut. 
CONTRACTION,  from  cow,  together,  and  traho,  to  draw;   the  state  of 

being  drawn  into  a  narrow  compass. 
CONVERGENT,  from  con,  together,  and  vergo,  to  bend ;  tending  to  one 

point  from  various  parts. 
CONVECTION,  from  con,  together,  and  veho,  to  carry  ;  the  power  in  fluids 

of  transmitting  heat  or  electricity  by  currents. 
CONVEX,  from  con,  together,  and  veho,  to  carry  ;  curved  outwardly,  or 

protuberant. 

CORPUSCULAR,  from  corptts,  a  body  ;  composed  of  or  relating  to  atoms. 
CORUSCATION,  from  corusco,  to  flash  or  shine  ;  a  flash,  or  quick  vibra- 
tion of  light. 
CRUCIBLE,  from  crux,  crucis,  a  cross;  a  little  pot,  such  as  goldsmiths 

melt  their  gold  in  ;  so  called  from  having  a  cross  impressed  upon'it. 
CRYOPHORUS,  from  xyro?,  cold,  and  iptQoi,  to  produce;  an  instrument 

i'or  showing  the  relation  between  evaporation  at  low  temperatures 

and  the  production  of  cold. 
CRYSTALOGRAPHY,  from  xoi'araMoc,  a  crystal,  and  y^acpcu,  to  describe; 

the  science  which  treats  of  crystals. 
CRYSTAL, -LINE,  from  xQi'aTaU.os,  ice;  a  substance  having  a  regular 

form,  as  rock-crystal,  which  resembles  ice. 
CRYSTALLIZATION  ;    the  formation  of  crystals  during  the  passage  of 

certain  bodies  from  a  fluid  to  a  solid  form. 
CUBE,  -ic ;  a  solid  figure,  contained  by  six  equal  squares. 

D. 

DECOMPOSITION  ;  the  resolution  of  a  compound  body  into  its  compo- 
nent parts. 

DECREMENT,  from  decresco,  to  grow  less;  the  quantity  by  which  any 
thing  decreases  or  becomes  less. 


376  Glossary. 

1) F n. A G RATION,  from  dcflagro,  to  burn  ;  burning. 

DEFLECTION,  from  de,  from,  and  fiecto,  to  bend  ;  a  turning  aside  out 
of  the  straight  way. 

DEGREE,  from  </«,  down,  and  gradus,  a  step ;  a  quantity  in  measure- 
ment —  as,  in  geometry,  the  300th  part  of  the  circumference  of  a 
circle. 

DELIQUESCENCE,  from  deliquto,  to  melt ;  a  gradual  melting,  caused  by 
the  absorption  of  water  from  the  atmosphere. 

DENSITY,  from  dcnsus,  thick;  vicinity  or  closeness  of  particles. 

DEPHLOGISTICATEIJ;  deprived  of  phlogiston,  the  supposed  principle 
of  inflammability. 

DETONATION,  from  dctoiw,  to  thunder;  explosion,  accompanied  with 
noise. 

DIAMETER,  from  a*u,  through,  and  ptTQor,  a  measure;  the  line  which 
passes  through  the  centre  of  a  circle,  or  of  any  other  curvilinear 
figure. 

DIAPHANOUS,  from  Jiu,  through,  and  </>«.Vo«,  to  shine;  that  which  allows 
a  passage  to  the  rays  of  Tight. 

DIATIIKHM ANOUS,  from  Jiu,  through,  and  StQuof,  heat;  that  through 
which  heat  will  pass  is  said  to  lx?  diatheriuanous. 

DILATATION,  from  dtjfero,  to  bear  apart ;  the  act  of  extending  into 
greater  space. 

DIMORPHOUS,  from  4t<,  twice,  and  MOQ<P»,,  a  form;  having  two  forms. 

Disc,  from  discus,  a  quoit ;  the  apparent  surface  of  a  heavenly  body. 

DISINTEGRATION,  from  rfi*,  meaning  separation,  and  integer,  wh<>!<  ; 
an  utter  separation  of  particles. 

DISPERSION,  -IVE,  from  di,  in  different  directions,  and  sparge,  to  scat- 
ter ;  the  act  of  scattering. 

DISRUPTION,  from  dis,  in  different  directions,  and  rumpo,  to  break ; 
the  act  of  tearing  asunder. 

DISSECTION,  from  disseco,  to  cut  to  piece* ;  the  act  of  separating  into 
pieces. 

DISTILLATION  ;  separation  drop  by  drop ;  the  process  by  which  a  fluid 
is  separated  from  another  substance,  i>y  first  being  converted  into 
vapor,  and  afterward  condensed  drop  by  drop. 

DIVEM.KNT,  from  direlloy  to  tear  asunder;  that  which  causes  sepa- 
ration. 

DIVERGENT,  from  rfi,  in  different  directions,  and  rxrgo,  to  bend  ;  tend- 
ing to  various  parts  from  one  point. 

DODECAHEDRON,  from  f*..,rUxu,  twelve,  and  »<Joa,  a  base  or  side;  a  solid 
figure  contained  by  twelve  equal  sides. 

DYNAMICS,  -ICAL,  from  'V,lU«.,  power;  that  branch  of  mechanical  sci- 
ence which  treats  of  moving  powers,  and  of  the  action  of  forces 
on  solid  bodies,  wnen  the  result  of  that  action  is  motion. 

£. 

F.Bft.MTiON,  from  rhtillin,  to  boil ;  the  act  of  boiling. 

EFFLORESCENCE,  from  efflorescn,  to  blow,  as  a  flower ;  the  formation 
of  small  crystals  on  the  surfaces  of  bodies,  in  cons. -<\\\< -nee  of  the 
abstraction  of  moisture  from  them  by  the  atmosphere. 

ELASTICITY, -ic,  from  «Aot'io»,  to  push  or  thrust;  the  property  bodies 
possess  of  resuming  their  original  form  when  pressure  is  re- 
moved. 

ELECTRODE,  from  ^exroor,  electricity,  and  o<?oc,  a  way;  the  point  at 
which  an  electric  current  enters  or  quits  the  body  through  which 
it  passes. 


Glossary.  377 


ELECTROGRAPHY,   from   ifitxTnov  and  y^utpw;    a  method  of  copying 

medals,  copperplate,  <fcc  ,  by  galvanism. 
ELECTROLYSIS,  -LYTE,  &c.,  from    j;Aa*T(>ov,   electricity,  and   Ai/w,  to 

loosen  ;  the  act  of  decomposing  bodies  by  electricity. 
ELECTRO-MAGNETISM  ;  magnetism  produced  by  electricity. 
ELECTROMETER;  an  instrument  for  ascertaining  the  quality  and  quan- 

tity of  electricity  in  electrified  bodies. 

ELECTROPHORUS  ;  an  instrument  for  producing  electricity. 
ELECTROSCOPE  ;  an  instrument  for  exhibiting  the  attractive  and  re- 

pulsive agencies  of  electricity. 
ELEMENT,  -ARY,  from  clcmentum,  an  element;  that  which  cannot  be 

resolved  into  two  or  more  parts,  and  contains  but  one  kind  of 

ponderable  matter. 
ELLIPSE,  from  *x,  deficiently,  and  A*//rw,  to  leave;  one  of  the  conic 

sections,  formed  by  the  intersection  of  a  plane  and  a  cone,  when 

the  plane  makes  a  less  angle  with  the  base  than  that  formed  by 

the  base  and  the  side  of  the  cone. 
EMPIRICAL,  from  *r,  in,  and  TreiQuotiai,  to  make  trial  ;  that  which  is 

made  or  is  done  as  an  experiment,  independently  of  hypothesis  or 

theory. 
EMPYREUMATIC,  from  «>,  in,  and  TTV^,  fire  ;  having  the  taste  or  smell 

of  burned  animal  or  vegetable  substances. 
ENDOSMOSE,  from  MtJor,  within,  and  <bauoq,  the  act  of  pushing;  a  flow- 

ing from  the  outside  to  the  inside. 
EPIDERMIS,  from  i/ii,  upon,  and  di'yua,  the  skin;  the  exterior  layer  of 

the  skin. 
EQUILIBRIUM,  from  <equus,  equal,  and  libra,  a  balance  ;  the  state  of  rest 

produced  by  forces  equally  balancing  one  another. 
EQUIVALENT,  from   aquus,  equal,  and  valco,  to  be  worth  ;   equal  in 

value. 

ETIOLATION  ;  the  blanching  of  vegetables  by  exclusion  from  light. 
EVAPORA'I  ION  ,  from  e,  out,  and  vapor,  vapor  ;    thfc   conversion  of  a 

liquid  into  vapor. 
EXOSMOSK,  from  £';<»,  without,  and  «(?><«$,  the  act  of  pushing;  a  flow- 

ing from  the  inside  to  the  outside. 
EXPANSION,  from  expando,  to  open  out;  the  enlargement  or  increase 

in  the  bulk  of  bodies,  which  is  produced  by  heat. 
EXPERIENCE,  from  ezperior,  to  attempt,  to  try  ;  knowledge  gained  by 

observation. 
EXPERIMENT;   something  done  in  order  to  discover  an  uncertain  or 

unknown  effect. 
EXPLOSION,  from  ez,  out,  and  plaudo,  to  utter  a  sound  ;  a  sudden  ex- 

pansion of  an  elastic  fluid,  with  force  and  a  loud  report. 

F. 

FERRUGINOUS,  from/errtm,  iron;  of  iron. 

FILTER  ;  a  strainer. 

FILTRATION  ;  the  process  whereby  liquids  are  strained. 

FLEXURE,  from  flecto,  to  bend  ;  the  act  of  bending;  also,  the  bend  or 

curve  of  a  line  or  figure.  « 

Focus,  -CAL,  from/ocus,  a  fireplace  ;  a  point  in  which  a  number  of  rays 

of  light  or  heat  meet,  after  being  refracted  or  reflected. 
FORMULA  ;  a  general  theorem;  it  is  called  algebraic,  logarithmic,  &c.7 

according  to  the  branch  of  mathematics  to  which  it  relates. 
FRICTION,  from/rico,  to  rub;  the  rubbing  or  grating  of  the  surfaces  of 

32* 


378  Glossary. 

bodies  upon  one  another  ;  also,  the  retarding  force  caused  by  this 
rubbing  of  surfaces  together. 

G. 

GALVANISM,  from  Professor  GALVANI  ;  current  electricity  is  sometimes 

so  called. 

GALVANOMETER;  an  instrument  for  measuring  galvanism. 
GAS,  -EOUS  ;  a  term  first  introduced  by  VAN  HELMONT  ;  a  permanent, 

aeriform  fluid. 

GELATINOUS,  from  gclo,  to  freeze  ;  resembling  jelly. 
GONIOMETER,  from  /cor/a,  an  angle,  and  /UT^OI,  a  measure  ;  an  instru- 

ment for  measuring  angles.  '  * 

GRAVITATION,  from  gravis,  heavy;  the  abstract  power  which  draws 

bodies  towards  each  other's  centres. 
GRAVITY,  from  gravu,  heavy  ;  the  natural  tendency  of  bodies  to  fall 

towards  a  centre. 
GRAVITY,  SPECIFIC  ;  the  relative  gravity  of  a  body  considered  with 

regard  to  some  other  body,  which  is  assumed  as  a  standard  of 

comparison. 

H. 


HALO,  from  tiJwc,  a  crown  ;  a  luminous  circle,  appearing  occasionally 
around  the  heavenly  bodies,  but  more  especially  about  the  sun 
and  moon. 

HELIOGRAPHIC,  from  v*io?,  the  sun,  and  y<ntyo»,  to  write;  delineated 
by  the  sun. 

HELIX,  from  »xio0o>,  to  twist  round  ;  a  screw  or  spiral. 

HEMISPHERE,  from  »>«oic,  half*  and  o<fi«()a,  a  sphere;  the  half  of  a 
sphere,  formed  by  a  plane  passing  through  the  centre. 

HERMETIC  SEAL  ;  when  the  neck  of  a  glass  vessel  or  tube  is  heated 
to  the  melting  point,  and  then  twisted  with  pincers  until  it  be 
air-tight,  the  vessel  or  tube  is  said  to  be  hermetically  scaled,  nr  to 
have  received  the  seal  of  Hermes,  the  reputed  inventor  of  chem- 

HETEROOF.NEOUS,  from  Vrtpoc,  different,  and  y*ioc,  kind;  different  in 

nature  and  properties. 
HOMOGENEOUS,  from  u^oc,  alike,  and  y*ro;,  kind;  alike  in  nature  and 

properties. 
HORIZONTAL,  from  6qi~wt  to  bound  or  terminate  ;  parallel  to  the  hori- 

zon. 
HYDRATE,  from  riJop,  water  ;  any  uncry  stall  ized  substance  which  con- 

tains water  in  a  fixed,  definite  proportion. 
HYDRO,  when  prefixed  to  the  name  of  a  chemical  substance,  denotes 

that  hydrogen  enters  into  the  composition  of  the  substance  which 

it  signifies. 
HYDROMETER,  from  txhup,  water,  and  ^frQovt  a  measure  ;    an  instru- 

ment for  comparing  the  density  and  gravity  of  liquids  with  water. 
HYDROSTATICS,  from  \-8uiQ,  water,  and  OT«TO$,  standing  ;  that  branch 

of  natural  philosophy  which  treats  of  the  pressure  and  equilibrium 

of  non-elastic  fluids,  and  also  of  the   weight,  pressure,  &c.,  of 

solids  immersed  in  them. 
HYGROMETER,  from  vyyoc,  moist,  and  ««'rnor,  a  measure;  an  instru- 

ment for  ascertaining  accurately  the  quantity  of  moisture  in  the 

atmosphere. 
HYGROSCOPE,  from  t'y(>6$,  moist,  and  <TXO.T*O>,  to  consider  ;  an  instru- 

ment for  exhibiting  apuroximatively  the  moisture  of  the  atmos- 

phere. 


Glossary.  379 

HYPO,  from  rno,  under  ;  when  prefixed  to  a  word,  denotes  an  inferior 
quantity  of  some  ingredient  which  enters  into  the  composition  of 
the  substance  which  it  signifies. 

HYPOTHESIS,  -TICAL,  from  i-v/«>,  under,  and  Ti&rju,  to  place  ;  a  princi- 
ple supposed  or  taken  for  granted  in  order  to  prove  a  point  in 
question. 

1. 

IMPINGING,  from  impingo,  to  strike  against;  dashing  against. 

INCANDESCENT,  from  incandesce,  to  grow  white  ;  white  or  glowing 
with  heat. 

INCIDENCE,  from  in,  upon,  and  cadotto  fall;  the  direction  in  which 
one  body  falls  on  or  strikes  another  ;  the  angle  which  the  moving 
body  makes  with  the  plane  of  the  body  struck,  is  called  the  "  angle 
of  incidence.'' 

INCREMENT,  from  incresco,  to  increase;  the  quantity  by  which  any 
thing  increases  or  becomes  greater. 

INDUCTION,  -IVE,  from  in,  to,  and  duco,  to  lead;  the  process  of  reason- 
ing? Dy  which  we  are  led  from  general  to  particular  truths. 

INDUCTION,  ELECTRICAL  ;  the  effect  produced  by  the  tendency  of  an 
insulated  electrified  body  to  excite  an  opposite  electric  state  in 
neighboring  bodies. 

INDUCTOMETER  ;  an  instrument  for  measuring  electrical  induction. 

INERTIA,  from  inertia,  inactivity;  the  disposition  of  matter  to  remain  in 
its  state  of  rest  or  motion 

INFLAMMABLE,  from  in,  and  flamma,  a  flame  ;  capable  of  burning  with 
a  tlame. 

INFLECTION,  from  in,  to,  and  facto,  to  bend. 

INSULATION,  from  insula,  an  island;  when  a  body,  containing  a  quan- 
tity of  free  heat,  or  of  electricity,  is  surrounded  by  non-conductors, 
it  is  said  to  be  insulated. 

INTEGRANT,  from  integer,  whole,  entire;  those  parts  of  a  body  which 
are  of  the  same  nature  with  the  whole,  are  called  integrant. 

INTERSTICES,  from  interstitium,  a  break  or  interval;  the  unoccupied 
spaces  between  the  molecules  of  bodies. 

IRIDESCENT,  from  iris,  the  rainbow;  marked  with  the  colors  of  the 
rainbow. 

ISOMERIC,  from  i'oog,  equal,  and  ufgog,  a  part;  substances  which  con- 
sist of  the  same  ingredients,  in  the  same  proportion,  and  yet  differ 
essentially  in  their  properties,  are  called  isomeric. 

ISOMERISM  ;  that  portion  of  chemical  science  which  treats  of  isomeric 
substances. 

J. 

JUXTAPOSITION,  from  juxta,  near,  and  pono,  to  place  ;  the  placing  of  one 
thirig  close  to  another. 

L. 

LAMINA,  from  lamina,  a  thin  plate ;  extremely  thin  plates,  of  which 
some  solid  bodies  are  composed. 

LENS,  from  lens,  a  bean ;  properly  a  small  glass  in  the  form  of  a  bean  ; 
but  more  generally  it  means  a  piece  of  glass,  or  other  transparent 
substance,  having  its  two  surfaces  so  formed  that  the  rays  of  light, 
in  passing  through  it,  have  their  direction  changed,  and  are  made 
to  diverge  or  converge,  or  to  become  parallel  after  diverging  or 
converging. 

LEVIGATION,  from  tews,  smooth ;  the  art  of  reducing  to  a  light  powder. 


Glossary. 

LIQUEFACTION,  from  liquefacio,  to  make  liquid ;  the  process  of  convert- 
ing Into  a  liquid  state. 

LITMDS  ;  a  blue  pigment  obtained  from  the  lichen  rocella;  it  is  a  most 
delicate  test  of  acids,  which  turn  it  red. 

LOADSTONE,  i.e.,  LEADSTONE  ;  an  ore  of  iron  having  magnetic  properties. 

M. 

MAGNET,  from  Magnesia,  a  town  in  Asia  Minor ;  artificial  magnets  are 

small  bars  of  steel  or  iron,  which,  when  placed  at  liberty,  turn  one 

end  to  the  north. 
MAGNETISM  ;  the   peculiar  property  possessed  by  certain  ferruginous 

bodies,  whereby,  under  certain  circumstances,  they  attract  and  re- 
pel one  another  according  to  certain  laws. 
MAGNETO-ELECTRICITY  ;  electricity  produced  by  magnetism. 
MALLEABLE,  from  malleus,  a  hammer ;  that  which  is  capable  of  being 

spread  by  beating. 
MAXIMUM,  from  maximum,  greatest;  the  greatest  value  of  a  variable 

quantity. 
MECHANICS,  from  tuixav',i  a  machine;  the  science  which  treats  of  the 

laws  of  the  rest  and  motion  of  bodies. 
METALLURGY,  from  p«'raJUor,  a  metal,  and  fyj-oi,  a  work ;  the  art  of 

working  metals,  and  separating  them  from  their  ores. 
MINERALOGY  ;  the  science  which  treats  of -bodies  not  being  vegetable 

or  animal. 
MOIRKE  METALLIQUE,  from  molrtc,  a  watered  silk  ;  when  tin  plates  are 

washed  over  with  a  weak  acid,  the  crystalline  texture  of  the  tin 

becomes  apparent,  forming  a  crystalline  appearance,  which  has  been 

called  Moirce  Metallique. 
MOLECULES, -AR,  a  diminutive  from  moles,  a  mass;  the  infinitely  small 

material  particles  of  which  bodies  are  conceived  to  be  a<rirr<-<r:iti<.ns. 
MOMENTUM,  from  nwreo,  to  move  ;  the  product  of  the  numbers  which 

represent  the  quantity  of  matter  and  the  velocity  of  a  body,  is 

called  its  momentum  or  quantity  of  motion. 
MUCILAGINOUS  ;  resembling  mucilage  or  gum. 
MULTIPLE,  from  multiplico,  to  render  manifold ;  a  quantity  is  said  to  be 

a  multiple  of  another  when  it  contains  that  other  quantity  a  certain 

number  of  times  without  a  remainder. 


NASCENT,  from  nascor,  to  be  born  ;  in  the  moment  of  formation. 

NEGATIVE,  from  nego,  to  deny  ;  quantities  to  which  the  sign  of  subtrac- 
tion, or  negative  sign,  is  prefixed,  are  called  negative  quantities ; 
this  sign  is  also  used  to  denote  operations  which  are  the  reverse 
of  those  denoted  by  the  positive  sign. 

NODES, -AL,  from  noting,  a  knot;  in  the  doctrine  of  curves,  a  node  is  a 
small  oval  figure  made  by  the  intersection  of  one  branch  of  a  curve 
with  another. 

NORMAL,  from  norma.,  a  rule ;  according  to  rule. 

NUCLEUS,  from  nucleus,  a  kernel ;  the  central  parts  of  a  body,  which  are 
supposed  to  be  firmer,  and  separated  from  the  other  parts,  as  the 
kernel  of  a  nut  is  from  the  shell ;  also,  the  point  about  which  mat- 
ter is  collected. 

O. 

OBLATE,  from  ob,  in  front  of,  and  lotus,  broad ;  flattened  or  short- 
ened. 


Glossary.  381 

OBLONG,  from  ob,  in  front  of,  and  longus,  long  ;  greater  in  length  than 
in  breadth. 

OCTOHEDRON,  -AL,from  oxrd>,  eight, and  'ffya,  a  side;  a  solid  figure  con- 
tained by  eight  equal  and  equilateral  triangles. 

OLEFIANT  GAS,  from  oleum,  oil,  and  Jio,  to  become  ;  a  colorless,  taste- 
less gas,  which  derives  its  name  from  its  property  of  forming  an 
oil-like  liquid  with  chlorine. 

OPTICS,  from  onrouai,  to  see  :  that  branch  of  natural  philosophy  which 
treats  of  vision,  and  of  the  nature  and  properties  of  light,  and  of  the 
various  changes  it  undergoes. 

ORGANIC  MATTER,  from  ooyuior,  an  organ  ;  when  matter  possesses  or- 
gans, or  organized  parts  for  sustaining  living  action,  as  animals  and 
plants,  it  is  called  organic. 

ORGANIZATION  ;  construction  in  which  the  parts  are  so  disposed  as  to 
be  subservient  to  each  other. 

OSCILLATION,  from  oscillor,  to  swing;  the  vibration  or  reciprocal  ascert 
and  descent  of  a  pendulum. 

OXIDE  ;  a  combination  with  oxygen,  not  being  acid. 

OXIDIZABLE  ;  capable  of  being  converted  into  an  oxide. 

OXYGEN,  from  oi-ug,  acid,  and  yervuw,  to  produce  ;  a  colorless,  aeriform 
fluid,  which  was  formerly  supposed  to  be  the  universal  acidifying 
principle. 

P. 

PARABOLA,  from  Tra^u,  parallel  to,  and  j$uAAu>,toplace;  one  of  the  conic 
sections,  formed  by  the  intersection  of  a  plane  and  a  cone,  when  the 
plane  passes  parallel  to  the  side  of  the  cone. 

PARALLEL  ;  a  term  applied  in  geometry  to  lines  and  planes,  which  are 
every  where  equidistant  from  one  another;  straight  lines,  which, if 
infinitely  produced,  never  meet,  are  called  parallel  straight  lines. 

PARALLELOGRAM  ;  a  four-sided  figure,  of  which  the  opposite  sides  are 
parallel  and  equal. 

PARALLELOPIPEDON  :  a  solid  figure  contained  by  six  parallelograms, 
the  opposite  sides  of  which  are  equal  and  parallel. 

PELLICLE,  a  diminutive  from  pellis,  a  skin  or  crust ;  a  thin  crust  formed 
on  the  surface  of  a  solution  by  evaporization. 

PENDULUM,  from  pcndeo,  to  hang;  a  heavy  body  so  suspended  that  it 
may  vibrate,  or  swing  backward  and  forward  about  some  fixed 
point,  by  the  action  of  gravity. 

PERCOLATE,  from  prr,  through,  and  coJo,  to  strain  ;  to  strain  through. 

PERM  KATE,  from  perm?o,  to  pass  through  ;  to  penetrate. 

PERPENDICULAR  ;  the  straight  line  which,  standing  upon  another 
straight  line,  makes  the  adjacent  angles  equal,  and  consequently 
right  angles,  is  said  to  be  perpendicular  to  the  line  upon  which  it 
stands. 

PHENOMENON,  from  (pairouai,  to  appear;  an  appearance. 

PHILOSOPHY, -ICAL,  from  (/uAt'w,  to  love,  and  ooyia,  wisdom  ;  the  study 
or  knowledge  of  nature  or  morality,  founded  on  reason  and  expe- 
rience, the  word  originally  implying  "  a  love  of  wisdom." 

PHLOGISTON,  from  <p^yt.>,  to  burn  ;  a  name  given  by  the  older  chemists 
to  an  imaginary  substance,  which  was  considered  as  the  principle 
of  inflammability. 

PHOSGENE,  from  <pwe,  light,  and  yswuw,  to  produce;  produced  by  light. 

PHOSPHORUS,  from  rp«c,  light,  and  (pot»,  to  produce;  a  highly  inflam- 
mable substance,  obtained  from  calcined  bones,  which  emits  light 
when  placed  in  the  dark. 


382  Glossary. 

PHOTOMETER,  from  yn?,  light,  and  ptrgov,  a  measure;  an  instrument 
for  measuring  the  different  intensities  of  light. 

PHYSIOLOGY, -ICAL,  from  oi'o/c,  nature,  and  iuvos,  an  account;  the 
science  which  treaU  of  the  structure  of  living  beings. 

PNEUMATICS,  from  Tirtrua,  air;  that  branch  of  natural  philosophy 
which  treats  of  the  weight,  pressure,  and  elasticity  of  aeriform  fluids. 

POLARITY;  the  opposition  of  two  equal  forces  in  bodies,  similar  to  that 
which  confers  the  tendency  of  magnetized  bodies  to  point  to  the 
magnetic  poles. 

POLARIZATION  ;  the  communication  of  the  above  opposition  of  forces. 

POLARIZED  LIGHT;  light  which,  by  reflection  or  refraction  at  a  certain 
angle,  or  by  refraction  in  certain  crystals,  has  acquired  the  prop- 
erty of  exhibiting  opposite  effects  in  planes  at  right  angles  to  each 
other,  is  said  to  be  polarized. 

POLES  OF  A  MAGNET  ;  points  in  a  magnet  where  the  intensity  of  the 
magnetic  force  is  a  maximum ;  one  of  these  attracts,  and  another 
repels,  the  same  pole  of  another  magnet. 

PORES,  from  ;ro(»o$,  a  passage ;  the  small  interstices  between  the  solid 
particles  of  bodies. 

PRECIPITATION,  from  prctcipito,  to  fall  suddenly;  the  separation  of  a 
solid  from  a  liquid ;  a  triangular  glass  solid  used  for  the  separation 
of  rays  of  light  by  refraction. 

PROJECTILE,  from  pro,  forward,  and  jacio,  to  throw;  a  heavy  body  pro- 
jected, or  cast  forward  into  •pace,  by  any  external  force. 

PROPORTION  ;  the  relation  of  equality  subsisting  between  two  ratios. 

PYROMETER,  from  nvQ,  fire,  and  ut'r^ov,  a  measure  ;  an  instrument  for 
measuring  higher  degrees  of  temperature  than  can  be  ascertained 
by  a  thermometer. 

PYROXYHC  SPIRIT,  from  nvg,  fire,  and  o«i;f,  acid  ;  a  colorless,  transpa- 
rent spirit,  obtained  by  the  destructive  distillation  of  wood. 

PYRO  ;  when  prefixed  to  a  word,  denotes  that  the  substance  which  it 
signifies  has  been  formed  at  a  high  temperature. 

PHOTOGRAPHY,  from  9.0*,  light,  and  yguyoi,  to  write  ;  writing  with  the 
sun's  rays. 

Q. 

QUADRANT  ;  the  fourth  part  of  the  circumference  of  a  circle. 

R. 

RADIATION,  from  radius,  a  ray;    the  shooting  forth  in  all  directions 

from  a  centre. 

RADICAL,  from  radix,  a  root;  the  original  principle  of  a  compound. 
RADIUS  ;  the  straight  line  drawn  from  the  centre  to  the  circumference 

of  a  circle. 
RAREFACTION,  from  rarus,  rare,  and /««'<?,  to  make  ;  the  act  of  causing 

a  substance  to  become  less  dense  ;  it  also  denominates  the  state  of 

this  lessened  density. 
RATIO  ;  the  relation  which  subsists  between  two  quantities  of  the  same 

kind,  the  comparison  being  made  by  considering  what  multiple 

part  or  parts  one  of  them  is  of  the  other. 
RAY  ;  a  beam  of  light  propagated  from  a  radiant  point. 
REACTION  ;  the  reciprocation  of  any  impulse,  or  force  impressed,  made 

by  the  body  on  which  such  impression  is  made.     Reaction  is  always 

equal  to  action. 
RECTANGLE,  fr^n  rectos,  right,  and  angulus,  an  angle  ;  a  four-sided  plane 


Glossary.  383 

figure,  in  which  all  the  angles  are  right  angles,  and  its  opposite 

sides  equal  and  parallel. 
RECTIFICATION;  the  process  of  drawing  any  thing  off  by  distillation,  in 

order  to  make  it  more  pure  and  refined. 
RECTILINEAR  ;  consisting  of,  or  bounded  by,  straight  lines. 
REFLECTION,  from  re,  back,  saidflecto,  to  bend  ;  the  act  of  bending  back  ; 

when  rays  of  light  fall  on  the  surfaces  of  bodies,  part  of  them  are 

thrown  back  or  reflected. 
REFRACTION,  from  re,  back,  a.ndfrango,  to  break;  the  deviation  of  rays 

of  light  from  their  direct  course,  when  passing  through  media  of 

different  densities. 

REFRANGIBLE;  susceptible  of  refraction. 

REFRIGERATION,  from  re,  again,  a.ndfrigo,  to  cool;  the  act  of  cooling. 
REPULSION,  from  re,  back,  and  pe//o,  to  drive  ;  that  property  in  certain 

bodies  whereby  they  mutually  tend  to  recede  and  fly  on  from  each 

other. 
RETORT,  from  re,  back,  and  torqueo,  to  twist ;  a  vessel  with  a  bent  neck, 

which  is  made  use  of  in  chemical  operations. 
RHOMBUS  ;  a  figure  which  has  all  its  sides  equal,  but  its  angles  are  not 

right  angles. 

RHOMBOHEDRON;  a  solid  figure,  whose  sides  are  composed  of  rhombs. 
RHOMBOID  ;  a  figure  which  has  its  opposite  sides  equal,  but  all  its  angles 

are  not  equal,  neither  are  all  its  angles  right  angles. 


SALIFIABLE  BASES,  from  sal,  salt,  and  fio,  to  become;  bodies  capable 
of  combining  with  acids  to  form  salts. 

SATURATION, -ATED,  from  satur,  full ;  the  solution  of  one  body  in  an- 
other until  the  receiving  body  can  contain  no  more. 

SCALE,  from  scala,  a  ladder  ;  an  instrument  in  which  a  line  is  divided 
into  small  and  equal  parts,  and  which  is  applied  for  the  purpose  of 
ascertaining  the  relative  dimensions  of  other  lengths  not  so  divided. 

SECTION,  from  scco,  to  cut ;  a  cutting,  or  part  separated  from  the  whole. 

SEGMENT  OF  A  CIRCLE  ;  any  portion  cut  off  by  a  straight  line. 

SINE  ;  the  straight  line  drawn  from  one  extremity  of  an  arc,  perpen- 
dicular to  the  radius  which  passes  through  the  other  extremity. 

SOLUTION,  from  so/vo,  to  loosen  ;  in  chemical  language,  any  fluid  that  con- 
tains another  substance  dissolved  in  and  intimately  mixed  with  it. 

SOLVENT;  any  substance  which  will  dissolve- another. 

SPECIFIC,  from  species,  a  particular  sort  or  kind;  that  which  denomi- 
nates any  property  which  is  not  general,  but  is  confined  to  an  in- 
dividual or  species. 

SPECTRUM  ;  the  colored  image  formed  on  a  white  surface  by  rays  of 
light  passing  through  a  hole,  and  being  refracted  by  a  glass  prism. 

SPHERE  ;  the  solid  figure  formed  by  the  rotation  of  a  semicircle  about 
its  diameter. 

SPHEROID,  -AL  ;  a  solid  figure,  formed  by  the  .revolution  of  an  ellipse 
about  one  of  its  axes ;  hence  it  is  sometimes  called  an  ellipsoid ; 
the  spheroid  will  be  oblate  or  prolate,  according  as  the  revolution 
is  performed  about  the  minor  or  major  axis  of  the  ellipse. 

STATICS,  -ICAL,  from  OTUTOC,  standing ;  that  branch  of  mechanical 
science  which  treats  of  the  equilibrium,  pressure,  weight,  &c.,  of 
solid  bodies  when  at  rest. 

STRATUM,  from  sterno,  to  strew  ;  a  layer. 

SYMMETRY,  -ICAL,  from  ovv,  together,  and  juc'rgov,  a  measure;  confor 
mity  of  measure. 


384  Glossary. 

SYNTHESIS,  from  ovv,  together,  and  TI#»;UI,  to  place;  the  composition 
of  a  whole  from  its  parts  ;  in  mathematics,  the  process  of  reasoning 
out  new  principles  from  those  already  established. 

SUBLIMATION,  from  sublimis,  high ;  the  act  of  raising  into  vapor  by 
means  of  heat,  and  condensing  in  the  upper  part  of  a  vessel. 

SYNCHRONOUS,  from  avr,  together,  and  /(>oroe,  time;  performed  in  the 
same  time. 

T. 

TACTILE,  from  tango,  to  touch;  of  or  relating  to  touch. 

TANGENT,  -IAL  ;  the  line  which  touches  a  circle  or  any  other  curve,  but 
does  not  cut  it. 

TERNARY,  from  ter,  thrice ;  containing  three  units. 

TETRAHEDRON,  from  T»'OOU«««,  four,  and  V<W,  a  base  or  side  ;  a  solid 
figure  contained  by  four  equal  and  equilateral  triangles. 

THEORY, -ETICAL,  from  ,9*f«i.'u,  a  view;  a  collected  view  of  all  that 
is  known  on  any  subject  into  one. 

THERMO-ELECTRICITY  ;  electricity  produced  by  heat. 

THERMOMETER,  from  tfty/uo?,  heat,  and  « /TOO r,  a  measure;  an  instru- 
ment for  measuring  the  degrees  of  heat. 

THERMOSCOPE,  from  Vn>uog,  heat,  and  oxo/«'ui,  to  view  ;  an  instrument 
for  exhibiting  the  powers  of  heat. 

TIRE;  a  hoop  of  iron  used  to  bend  and  receive  the  felly  of  a  wheel. 

TORSION,  FORCE  or,  from  turqueo,  to  twist;  a  term  applied  by  Cou- 
lomb to  denote  the  effort  made  by  a  thread  which  has  been  twisted 
to  untwist  itself. 

TRANSPARENT  ;  a  term  to  denote  the  quality  of  a  substance  which  not 
only  admits  the  passage  of  light,  but  also  of  the  vision  of  external 
objects. 

TRITURATED,  from  trituro,  to  thrash  ;  reduced  to  powder. 

TRUNCATION,  from  trunru*,  cut  short ;  the  cutting  off  a  portion  of  a 
solid,  as  of  the  solid  angle  of  a  crystal. 

u. 

UNDULATION,  from  unda,  a  wave  ;  a  formation  of  waves. 
UNIAXAL,  from  unus,  one,  and  axis,  an  axis;  having  but  one  axis. 

V. 

VACUUM,  Latin  ;  a  space  empty  and  devoid  of  all  mattor. 
VENTILATION,  from  retitus,  wind;  the  supply  of  fresh  air. 
VERNIER;  an  instrument  invented  by  Vernier;  it  consists  of  a  small, 

movable  scale,  running  parallel  to  the  fixed  scale  of  a  quadrant  or 

other  instrument,  and  Raving  the  effect  of  subdividing  the  divisions 

of  the  instrument  into  more  minute  parts. 
VIBRATION,  from  vibro,  to  brandish  ;  the  regular  reciprocating  motion 

of  a,  body,  as  of  a  pendulum,  &c.;  a  motion  to  and  frg. 
VOLUME,  from  volumen,  a  roll ;  the  apparent  space  occupied  by  a  body. 

W. 

WEIGHT  ;  the  pressure  which  a  body  exerts  vertically  downward  in 
consequence  of  the  action  of  gravity. 

Z. 

ZERO  ;  the  numeral  0,  which  fills  the  blank  between  the  ascending 
and  descending  numbers  in  a  series. 


INDEX 


A  Page. 

Acetate  of  alumina 327 

ammonia 327 

copper 326 

iron 327 

lead ' 326 

mercury,  tin,  zinc 327 

Acetous  fermentation 34H 

Acid,  acetic 326 

antimonic 264 

antimonious 264 

apocrenic 331 

arsenic 257 

arsenious 255 

azulmic 331 

benzole 329 

boracic 208 

bromic 145 

camphoric 330 

carbazotic 331 

carbonic ....?.... 176 

chloric ; 139 

chlorous 1 39 

chloriodic 143 

chlorocarbonic 181 

chromic 259 

citric 327 

columbic 263 

crenic 331 

croconic 329 

cyanic 1 88 

cyanohydrosulphuric 200 

cyanuric 188 

elaidic 338 

ellagic 330 

fluosilicic 213 

fluoboric 209 

fulminic 188 

gallic 328 

hydriodic 156 

hydrobromic 1 57 

hydrochloric 154 

hydrofluoric 157 

hydroselenic 211 

33 


Acid,  hydrosulphoeyanic. . ..  200 

hydrosulphuric 197 

hydrosulphurous  .......   199 

hydrotelluric 263 

hy drothionic .   1 1)7 

hypochlorous 1 38 

hyponitrous 165 

hypophosphorous 202 

hy  posulphuric 1 94 

hyposulphurous 192 

indigotic 331 

Todic 143 

iodous 142 

kinic 329 

lactic 329 

malic 327 

margaric 330 

manganic 240 

meconic 329 

mellitic 329 

metagallic 330 

metameconic   329 

molybdic 262 

moroxylic 330 

mucic 330 

muriatic .  v 154 

nitric 166 

nitrohydrochloric 1 68 

nitrohydrofluoric 1 69 

nitrous 165 

nitromuriatic 169 

oxalic 325 

oleic 330 

paracyanuric 189 

paraphosphoric 204 

pectic 331 

perchloric 140 


permanganic. 


240 


periodic 143 

phosphoric 203 

Acidulous  springs 360 

Acid,  phosphorous 203 

•  1  Of\ 

prussic 18y 

.      •  *KMJ 

pyrocitnc «i^» 


386 


Indei. 


Acid,  pyrogallic 330 

pyroligneous 326 

pyrophosphoric 204 

racemic 329 

rocellic 330 

selenic 211 

selenious 210 

silicic 212 

silicohydrofluoric 213 

stearic 330 

succinic 330 

sulphuric 194 

sulphurous 192 

tannic 32H 

tnrtaric 327 

telluric 268 

trllurous 268 

titanic 267 

tungstic 262 

valerianic 330 

vanadic 

Affinity,  chemical 105 

disposing 147 

double 106 

effects  of 112 

elective 106 

measure  of Ill 

simple 1 06 

Air 160 

Alnbaster 290 

Albumen 349 

Alcohol 341 

Alkalies,  metallic  bases  of. . .  218 

Alkaline  earths 227 

Alloys  of  antimony 265 

copper 970 

gold 280 

lead 272 

manganese 24 1 

silver 277 

sodium  and  potassium. ..  225 

Alum ....*;).r..  294 

ammonia 294 

Alum  stone 294 

iron 294 

manganese 294 

Alkaline  springs 360 

Alumina 234 

Aluminium 234 

Aluminous  earth 234 

Amalgams 275 

Amber 340 

Ambergris 351 

Ammonia 170 


Analysis  of  carbonate  of  lime  358 
Analysis  of  minerals  ........   :r»7 

mixed  gases  ...........  356 

Angles  of  crystals  ..........  284 

plane  .................  284 

solid  ..................  284 

Analysis  of  mineral  waters..  360 
Anhydrite  .................  290 

Anthracite  .................   173 

Animal  acids  ...............  350 

chemistry  .  .  ...........  349 

heat  ..................  353 

oils  and  fats  ............  350 

Antimonio-sulphurets  .......  319 

Antimony  .................   V.MJ3 

Appendix  ........  ^  ........ 

Aqua  fortis  ................  168 

potass*  ................   •-'•-••> 


Aerostation  ....,...,.  .......  149 

Arrow-root  ............... 

Areeniates  ................. 

table  of  compounds  .....  H<H> 

Arsenic  .................. 

Arsenites  ..................  300 

Arsenio-sulphurets  ......... 

Arseniureted  hydrogen  .....  258 

Atomic  theory  .............  118 

Auro-chlorides  .............  319 

B 

Balloons  ...................  M!» 

Balaam  of  sulphur  ......... 

Balsam  ...................  340 

Barilla  .................... 

Barium  ................... 

Barometer  ................. 

Baryta  ....................  227 

Barytes    ..................  290 

Beltroetal  .  ................  270 

Biborate  of  soda  ............  308 

Bicarbonate  of  ammonia  .....  310 

potassa  ................  :'.!<) 

soda  ..................  310 

Bicarburet  of  nitrogen  ......  188 

Bichromate  of  potassa  .......  !$U7 

Bichloride  of  cyanogen  ......  189 

mercury  ...............  'J?  1 

platinum  ....>.  .........  ','-  1 

tin  ....................  JM 

titanium  ...............  »« 

tungsten  ..............  262 

Bicyanuret  of  mercury  ......  275 

Bile  .................  354 


Index. 


„       387 


Bichloride  of  molybdenum 

...  202 

180 

Biuiodidc  of  platinum.  .  .. 

.  .  .  282 

14r» 

.  ..  250 

lead 

O7<> 

.  ..  A28 

magnesium  ....... 

233 

.  ..  2(>3 

225 

Clipper  .  . 

.  ..  270 

1()7 

}  }       

...279 

phosphorus 

205 

hydrogen  

153 

091 

...  274 

selenium  .... 

211 

.  ..  •-><;] 

silicon  

213 

.  .  .   1  64 

zinc  

247 

.  ..  281 

..  202 

c 

tin   

.  .  .  '  250 

°47 

.  .  .  2<il 

Calcium  

230 

Biphosphuret  of  coba^.  .  . 

.  .  .  253 

Caloric  

25 

Bisilicatcs    .    .                   . 

;}]•) 

absorption  of. 

32 

Bismuth           

2(16 

conduction  of 

26 

1'!') 

effects  of 

3C 

232 

radiation  of 

20 

..  253 

reflection  of  

31 

..  244 

theories  . 

32 

mercury     

..  275 

Calomel  

274 

.  ..  282 

184 

tin 

251 

339 

.-.  211 

°'U 

titanium   

..  268 

Calori  motor  .. 

80 

Bisulphate  of  the  peroxide 

of 

341 

mercury             . 

203 

Carbon  ..... 

172 

..   289 

five-fourths  chloride  .  .  .  . 

181 

..  289 

308 

..  327 

300 

Bituminous  coal              .  .  .  . 

..  173 

310 

Blafk  dyes     

345 

lead     

311 

lead 

..  173 

lime  .  . 

310 

270 

'11  1 

.  .  243 

potassa  

3ft8 

.  .    137 

protoxide  of  iron 

310 

powder       

..  232 

soda  

300 

Blue  vitriol                   

.  .  2(*3 

strontia  

310 

Block  tin           .          .... 

.  249 

Carbonic  oxide    . 

176 

Blood                        

351 

Carbosulphatf  of  ammonia 

315 

Bone  phosphate  of  lime.  .  . 

.  .  304 

Carbosulohurets  .    ..                 . 

317 

.  355 

ammonia 

318 

..   307 

barium  

?}8 

.  .   308 

calcium  .  .  r  •           .... 

318 

..  207 

sulphuret  of  lithium 

318 

Bri«s 

..  270 

magnesium 

318 

.   143 

317 

Bromates  

..   302 
181 

sodium    

318 
241 

.  .  207 

'M5 

.  .  231 

Carmine  

34  r> 

,.  228 

Cast  iron.  . 

245 

388 


Index. 


Cassava    

...  336 

107 

Cementing  .  .  .  . 

:w,\ 

Cerin  

.  .  341 

'><;;* 

Cerite 

...  26G 

Complex  animal  substances.  . 

173 

351 

Chloral 

181 

lf>? 

CO  Dill 

baryta  .  .  . 

...  300 

9M4 

!£>*) 

...... 

9fW 

bismuth  

...267 

•.'7-4 

bromine  

.    1  l.'i 

3i>7 

cadmium  ......... 

248 

.  231 

181 

252 

3V7 

...  270 

•>-;; 

cyanogen  .  .           .  . 

.     188 

283 

lead  

...  272 

Crystallogenic  attraction  .... 

287 

232 

263 

226 

188 

233 

272 

nickel       

....  254 

•>."» 

..  221 

V41 

211 

954 

213 

977 

.  277 

9K» 

soda                    .... 

.  225 

947 

224 

99/> 

Tnbe 

KM 

tellurium 

268 

247 

360 

....  179 

D 

08 

*  *  "  "  „,.. 

284 

l.-ad  ^ 

...,.  307 
....  307 

„•> 

potassa  

307 
258 

Deliquesce  

287 
322 

Chyle                           

354 

197 

....  333 

Difluoborate  of  ammonia  .  .  .  . 

S16 

....  273 

Dipyrophosphate  of  soda 

184 

oxide  of  silver  

''  nation  of  metals 

.  217 

soda  and  basic  water  .... 

3ur> 

286 

17:> 

286 

]).  carbonate  protoxide  of  cop- 

3^1  1 

185 

Diahloride  of  copper  

....  251 

Dicarbonate  of  mercury  

311 

.  344 

Dicarburet  of  hydrogen  

1-2 

Digester,  Marcet's 

U: phosphate  of  potassa 

Diphosphate  of  ammonia 

lime 

magnesia 

Diphosphuret  of  iron 

Din i Irate  of  protoxide  of  lead 

mercury 

Diniodide  of  copper 

Dioxide  of  copper 

ijisuiphate  of  alumina 

pj-.iloxide  of  copper 

Disulphuret  of  iron 

nickel 

Dodecahedron '. 

Dolomite 

Double  bromides 

carbonates 

cyanurets 

iluorides 

iodides 

Drying  oils 

Ductility 


B 


Ebullition 
Effloresce 


Efaidin 

Elasticity 

Electricity    

Electrical  machine 

Electro-chemical    decomposi- 
tion   

Electrodes 

Electrography 

Electrometer,  gold  leaf. 

balance 

Electro-magnetism 

theory  

Electro-magnetic  multiplier. . 

Electrophorus 

Electrotype 

Emetia - 

Emulsion 

Essences 

Etching 

Etherine,   four-four    carburet 

of  hydrogen 

Ethers 

Ethiop's  mineral * . . 

Eudiometer 

Eudiometry 

Eupione 

33* 


li^dcx. 


55 
302 
304 
304 
304 
245 
297 
2.7 
270 
2(iO 
2;<1 

244 
254 

2eo 

2SO 
320 
312 
321 
321 
320 

215 


52 

247 

355 

338 

109 

72 

74 

90 

88 

104 

74 

77 

91 

100 

93 

77 

104 

334 

338 

339 

158 

184 
342 
275 
152 

163 

184 


389 


Evaporation 


59 


Febrifuge  salt  of  Silvius  .....  221 

Feathers  ..................  356 

Fermentation  ..............  345 

Fibrin...  ..................  349 

Filtration    .................   362 

Fire-clamp  .................    186 

Fixed  oils  .................  3:57 

Flowers  of  zinc  ............  247 

Fluoborate  of  ammonia  ......   315 

Fluoride  of  barium  ..........  228 

calcium  ...............  2:U 

lead  ...................  271 

lithium  ................  226 

magnesium  ............  233 

potassium  .............   221 

sodium  ......  ..........   225 

strontium  ..............  230 

zinc  ..................  247 

Fluorine  ..................   145 

Fluosilieate  of  ammonia  .....   315 

Food  of  plants  ..............  348 

Fowler's  arsenical  solution  .  .  306 
Freezing  mixtures  ..........     50 

Fulminating  gold  ...........   279 

platinum  ..............  282 

silver  .................  277 

Fuming  liquid  of  Libavius.  .  .   250 
Fusion  ....................   109 

Fusion,  watery  .............  287 

Fusibility  ..................  215 


G 

Galena 

Galvanism   * 

theories 

effects  of 

Gasometers 

Gas  lights 

Gastric  juice 

i  Gaseous  mixtures 

containing  carbonic   acid 

hydrogen 

nitrogen 

oxygen 

Gelatin 

Germ 

Germination 

Glass 

green  bottle 

crown 


plate 


271 

78 
'82 
84 
129 
184 
353 
356 
357 
357 
357 
356 
349 
347 
347 
213 
213 
213 
213 


390 


ftgfe, 


Glass,  flint ;  213 

Glauber's  salts 

Glucina    236 

Glucinium 236 

Glue 349 

Gluten 336 

Gold 

powder . . .- 280 

Green  vitriol 291 

Graphite 245 

Gum 336 

arabic    387 

Senegal 337 

tragacanth 337 

reams 340 

Gypsum 276 

H 

Hair 355 

Hartshorn 170 

1  h-mrtitr,  red 243 

brown 243 

Hexahedron 284 

Homberg's  pyrophorus £'4 

Hog's  lard ,..  350 

Hoiwy 335 

Howls 355 

Mom :r,:> 

Hordein 347 

Horn  silver 277 

Hydrates 152 

Hydriodate  of  ammonia 315 

Hydro-salts    314 

H  yd  roc  Morale  of  ammonia..  314 

Hydrobromate  of  ammonia..  315 

Hydrofluate  of  ammonia  ....  315 

I  lydrocyanate  of  ammonia. . .  31."» 

Hydrogen 146 

Hyduret  of  potassium 222 

Hygrometers 62 


Idrialine  184 

Ignition    70 

Induction 75 

Indefinite  proportions 114 

Indelible  ink 298 

India  rubber 341 

Ink    328 

Insolubility 108 

lodates 301 

lodate  of  potassa 301 

Iodide  of  barium 228 

calcium .  231 


Iodide  of  cadmium 
lead 


248 


magnesium  ............  £13 

silver  .................  v.'77 

sodium  ............  .".  .  .  225 

phosphorus  ............  20~> 

sulphur  ...............  l!>7 

potassium  ............. 

strontium.  .  .  .  .  .  ........  230 

zinc  ........  .  .........  -JI7 

Iodine  ....................  140 

Iron  ......................  241 

Iron  pyrites  ................  244 

Iridium  ...................  282 

Indochlorides  ..............  320 

Isomorphism  ...............  2n7 

Ivory-black  ................  17:; 

K 

Kalium  ...................  218 

Kermes  mineral  ........... 

Kelp  .....................  309 


Lakes -....  :,u 

Lamp-black 173 

Lapis  causticus 

Latanium 2H3 

Lead si?l 

Leyden  jar 76 

Light 

reflection  of (>•'> 

refraction  of 

decomposition  of <>7 

absorption  of 

Light  carbureted  hydrogen  . .  I    J 

Liquefaction 49 

Lignin 

Lime "..., 

Lime-water 'J30 

Liquorice :j:5T> 

Litharge i>71 

Lithia i>J6 

Lithium 

Litmus :'.!.'. 

Lucifer  matches 300 

Lunar  caustic 298 

M 

Madder 345 

Magnesium 232 

Magistery  of  bismuth 2<>7 

Magnesia i>33 


Index. 


391 


Magnetic  iron  pyrites 244 

Ma  trie    circle 9G 

Malleability 214 

Magneto-electric  induction . .     l.)'j 
Magneto-electric    machine  . .     99 

Manganese 238 

Manua 335 

Maigarine   351 

Massicot 271 

Matches 30C 

Membranes 355 

Mi-lair* 214 

Metallic  lustre 214 

Metaphosphates 305 

Mercury 273 

Mtlk 

Microcosmic  salt 303 

Mineral  green. 311 

Molasses 335 

Molybdosulphurets 318 

M.'.lybdosulphuret  of  potassa.  318 

Molybdenum 261 

M->rph:a 332 

Mosaic  gold 251 

Mucus 354 

Muscle 356 

Myricine 341 


Nails 355 

Naphtha 184 

Naphthaline 184 

Narcotina 333 

Natron 223 

Natural  substances 321 

Neutral  substances 334 

Nickel i 253 

Nicotina 334 

Nitre 295 

Nitric  oxide 164 

Nitrous  oxide 163 

Nituret  of  potassium 222 

Nitrates 295 

Nitrate  of  ammonia. . .  .* 296 

baryta 296 

lime 297 

magnesia 297 

potassa 295 

soda 296 

strontia 297 

protoxide  of  copper 297 

lead 297 

mercury 297 

oxide  silver 297 

Nitrites ." 299 


j  Nitrogen 153 

!  Nitrous  ether 343 

i  Notation ]26 

I  Nomenclature 122 

Ntuc  voinica 334 

O 

Oblique  prisms 285 

rhombic  prisms 285 

rectangular 285 

rhomboidal 285 

Octohedron 285 

Octohedron,  regular 286 

square  285 

rectangular 286 

rhombic 286 

OEnanthic  ether 342 

Oils 337 

Oily  acids 330 

Oil  gas 183 

Oleine 331 

Olefiant  gas 182 

Orpiment 258 

Osmium 282 

Osmazome 350 

Osmio-chlorides 320 

Oxalate  of  potassa 325 

of  lime 326 

Oxalic  ether „  343 

Oxigenation 133 

Oxidation 133 

Oxide  of  selenium 210 

cadmium 248 

carbon 196 

phosphorus 202 

titanium 267 

silver 277 

strontium 230 

Oxychlorides 320 

chromium 260 

Oxygen 128 

Oxysalts 287 

Oxysulphuret  of  antimony..  265 


Palladium 282 

Palladio-chlorides 319 

Palm-oil 339 

Paracyanuric  acid 189 

Paranaphthaline 184 

Parraffine 184 

Peat 173 

Pearlash 308 

Perbromide  of  phosphorus . . .  205 
Percarbureted  hydrogen 183 


392 


Percussion  powder <VX) 

Perchlorates 

Pefchloride  of  iron 243 

manganese 240 

phosphorus  

Periodide  of  arsenic 

iron 

carbon 181  I 

Perflworide  of  iron 244  j 

manganese 240  ' 

Pcrphosphuret  of  hydrogen . .  206  ' 

Peroxide  of  strontium 229  < 

calcium 

manganese 239 

iron 24:* 

cobalt 2T>2 

four-three  oxcobalt 252 

titanium 2l>7 

tellurium 268 

lead 271 

Permuriate  of  tin 250 

iVrsuhihuret  of  arsenic 258 

tellurium 268 

Perphosphuret  of  iron 245 

Pewter 265 

Phosphureted  hydrogen 206 

Phosphorus 200 

Phosphorescence 70 

Phosphates 302 

Phosphate  of  potassa 302 

soda  and  ammonia 303 

ammonia 304 

lime 304 

magnesia  and  ammonia. .  304 
Phosphuret  of  potassium  ....  2£2 

cadmium 249 

calcium 232 

manganese 241 

hydrogen 205 

barium 229 

Pitch 340 

Pinchbeck 270 

Photometers  .-.  .* 71 

Photographic  drawing 68 

Platinum 281 

spongy 2-1 

Platinochlorides 31 :  • 

biniodide  of  potassium. . .  320 

Plumbago 173 

Pneumatic  cistern 129 

Pot-metal 271 

Portable  gas 185 

Potassa 221 

hydrate  of. 221 

Polassa-fusa  . .  .  221 


Potassium 218 

Potash  and  pearlash 

Primary  forms 284 

Printer's  types 265 

Protobromide  of  iron 244 

potassium 

Protochloride  of  iron '.M: ; 

tin 250 

carbon 

manganese 

Protochloride  of  arsenic 

cerium 

mercury 

gold .* 

platinum 281 

uranium 

Protocyanuret  of  iron 

P  rot  iodide  of  iron .' 1  ' 

cadmium 248* 

carbon 1-1 

tin 

platinum 

Protohyduret  of  arsenic  .... 

Protoeulphuret  of  arsenic  .... 

platinum 

mercury 

cerium 

cobalt 

nickel 

manganese ','  II 

tin 

iron 

strontium 

calcium 

Protosulphocyanuret  of  iron . 

Protoxide  of  strontium 

ct-rium 

hydrogen  

bismuth '. 

nitrogen 

potassium 220 

gold 279 

sodium 224 

copper. 270 

lithium.........'.  . 

barium 227 

lead 271 

calcium 

•      magnesium '>'•'<•> 

mercury 273 

thorium 237 

manganese 2MS 

iron 242 

platinum 281 

zinc ii-17 


Index. 


393 


Protoxide  of  tin 249 

cobalt ; . . .  252 

nickel 253 

vanadium 201 

molybdenum 261 

uranium 2(i.> 

Proximate  principles 323 

Prussian  blue 243 

Pus 355 

Plumula   347 

Putrefactive  fermentation ....  346 

Pyrometers 37 

of  Wedgwood 46 

of  Daniell 46 

of  Brequet 46 

Pyrotechny 296 

Pyrophosphates 304 

of  soda 305 

Pyroxylic  spirit 343 

Q 

Quadrisilicates 313 

Quadrochloride  of  nitrogen  ..  169 

Quartation 278 

Q,uinia 333 

R 

Radicle 347 

Realgar 258 

Red  dyes 344 

Red  oxide  of  manganese 239 

lead , 272 

Red  precipitate . . .  t 274 

Respiration 180 

Resins 340 

I\espi  ration  of  plants 348 

Revolving  rectangle 94 

Right  prisms 284 

Right  square  prisms 284 

rectangular 284 

rhombic 284 

rhomboidal 284 

Rhodium 282 

Rhodio-chlorides 320 

Rhombohedron '.   285 

R.)chelle  salt 328 

llt.'ck  candy 335 

gait 224 

s 

Saccharine  fermentation 345 

Safety  lamp « 1 87 

Sago 336 

Sal-ammoniac 314 


Saliva 

Salifiable  base 

Saline  springs 

Saltpetre 

Salts  or  secondary  compounds 

double 

triple 

Sandarac 

Scheele's  green 

Sealing-wax 

Seleniuret  of  aluminium 

Seleniuret  of  potassium 

Selenium 

Sesquiphosphuret  of  alumini- 
um  

cobalt 

Sesquibromide  of  arsenic  .... 

carbonate  of  ammonia. . . 

carbonate  of  soda 

Sesquichloride  of  aluminium. 


antimony 
arsenic  . . 


cerium 

chromium 

uranium 

Sesquifluoride  of  chromium. . 
Sesquioxide  of  aluminium. . . . 

antimony 

bismuth 

cerium 

chromium 

glucinium 

manganese 

nickel 

platinum 

sodium 

tin 

uranium 

zirconium 

Sesquisulphuret  of  aluminium 

antimony 

arsenic 

chromium 

tin 

cobalt , 

Sesquisulphocyanuret  of  iron. 
Sulphocyanuret  of  barium.  . . 


iron. 


potassium 

Shells 

Silver 

Silver  glance  . 

Silex 

Silicon 


353 

283 
360 
296 
283 
288 
288 
254 
306 
340 
235 
222 


235 
253 
258 
310 
309 
235 
264 
257 
266 
260 
266 
260 
234 
264 
207 
266 
259 
236 
239 
254 
281 
224 
250 
266 
237 
235 
265 
258 
260 
251 
253 
245 
229 
245 
223 
355 
276 
277 
212 
212 


394 


Silicium 

Silica 

Silk 

Solution ' 

Spirituous  and  ethereal  sub- 
stances   

Spirits  of  turpentine 

Soaps  

Sodium 

Soda 

Solder -..¥# 

Specific  gravity 

of  essential  and  other  oils 

Spermaceti  oil 

Starch 

Steam .»  ...........  ;/ 

artillery 

engine 

generator 

8teeF. 

Stream  tin 

Strontia 

Strontium 

Strychnia 

Sugar 

SKT:::::::::::::: 

Subphnspharet  of  cobalt. . . . 

nickel 

Subsulphate  of  protoxide  of 

mercury 

Subsesquiphosphuret  of  cop- 
per   

Sublimation 

Suet 

Sulphur 

flowers  of. . . 

rool-brimstone 

Sulphates 

Sulphate  of  ammonia 

alumina 

baryta 

lime 

hthia 

potassa 

soda ...-  iV 

strontia 

potassa  and  alumina  .... 

potassa  and  magnesia. . . . 

protoxide  of  copper 

cobalt 


iron   

manganese 
mercury... 


212 

108 
341 

2S1 
224 

121 

3f>0 

335 

56 

59 

58 

58 

245 

•Jl:' 

U9 

:<;;:; 
334 

Ufl 
253 
254 

293 

270 
190 
350 
190 
190 
190 

He 

SB9 

291 
290 
290 
2H9 


880 

294 
2<>4 

L>  •_' 
291 


Sulphate  of  nickel 

silver £»3 

zinc 

Sulphureted  springs 

Sulphuret  of  barium 228 

boron 

bismuth 

cadmium 

cobalt 

copper 270 

Sulphuret  of  cyanogen 200 

lead «....  272 

potassium 

silicon 

sodium 

silver 

uranium 

zinc 

Sulphur-salts :<ir. 

Sulphuric  ether 342 

Sweat 

Sympathetic  ink 252 


Table  of  discovery  of  metals . .  fit 

Tannin 32H 

Tapioca 336 

Tar 340 

Tartar  emetic 

Tartrate  of  antimony 

potassa 

soda 

Tears....,....'.. 

Teeth.... 

Tellurium 

Tendons 

Terchloride  of  boron 

molybdenum 

gold 

chromium 260 

Terfluoride  of  chromium 260 

Teroxide  of  potassium 221 

Teriodide  of  nitrogen It .:  • 

Terphospliuret  of  t  n 251 

Tersulphate  of  alumina 

sesquioxide  of  chromium    '2112 

Tests  of  metallic  ores 

Teroxide  of  gold 279 

r/     potassium 

Tersulphuret  of  tin 

Tertrasulphuret  of  iron 

Theory  of  animal  heat 

Thermo-electricity 10'^ 

Thermometers 42 


Index. 


395 


Thermometers,  air 42 

differential 43 

mercurial 44 

graduating  of 44 

register * 45 

Thorina 237 

Thorium 237 

Tin. A 249 

Tinfoil 249 

Tincal 306 

Titanium 267 

Torpedoes 277 

Train  oil 350 

Trifluoborate  of  ammonia. . . .  315 

Triphosphate  of  potassa 302 

soda 303 

soda  and  basic  water....   303 

acid  triphosphate 303 

lime 304 

magnesia 304 

ox.  silver 304 

Triphosphuret  of  copper 270 

Trisilicates 313 

Trona 309 

Tungsten 262 

Tungstopulphurets..* 319 

Turkey  red 345 

Turpentine 340 

Turpeth  mineral 293 

U 

Ultimate  analysis 322 

Universal  cement 370 

Uranium 265 

Urine . . .  355 


Vanadium 260 

Vaporization 52 

Varietrated  copper  pyrites...  244 
Varvicite 240 


Vegetable   acids 325 

alkalies 332 

Verdigris 326 

Verditer 311 

Vermilion 275 

Vinegar,  distilled 326 

Vinous  fermentation 345 

Voltaic  electricity 78 

circles 79 

pile 81 

Volta-electric  induction 97 

Volatile 52 

oils 339 

liniment 338 

Volatility 215 

W 

Water 150 

of  crystallization 287 

of  nitre 167 

Water  gilding 280 

Wax 341 

White  oxide  of  arsenic 255 

White  vitriol 292 

Wollaston's  scale  of  chemical 

equivalents 364 

Wool 356 

Woulfe's  apparatus 155 


Yellow  dyes 345 

Yttria 236 

Yttrium 236 


Zaffre 252 

Zinc 246 

Zinc  blende 247 

Zinetum 246 

Zirconia 237 

Zirconium 237 


INDEX  OF   FIGURES. 


fig.  Page. 

1.  Conduclometer i»7 

2.  Apparatus  for  beating  liquids...    28 

3.  4.    "          for  cooduc'n  uf  liquids    -.-.» 

5.  "          for  radiation  of  cat...     :  > 

6.  "         for  reflection  of  caloric    31 

7.  Concave  mirror* 31 

8.  Pyrometers 37 

9.  10.  A  pp.  for  expansion  of  liquids    38 

11.  App.  for  expansion  of  air 99 

12.  Air  thermometer 42 

13.  Differential  thermometer 43 

14.  Common  and  laboratory  do 44 

15.  Blowpipes 4-1 

16.  Different  scale*  of  thermometers     45 

17.  Ri-gMer  thermometer 45 

18.  Metallic  thermometer 4G 

19.  Influence  of  pressure  on  the  boil- 

lug  point 53 

90.  Pulse  gla«a 53 

21.  App.  culinary  paradox... 64 

SB.  Marcet's  digester 55 

iritlarop 55 

94.  Steam  engine  illustrated 56 

85,  98.  Distillation.  Cryopborus..50,60 

97.  Apparatus  for  refraction  of  light.     67 

98.  Priwn 67 

99.  Gold  leaf  electrometer 74 

30.  Electrical  machine 75 

31.  Apparatus  for  I nd action 76 

39.  Electrophone 77 

33.  Balance  electrometer 77 

34.  Simple  voltaic  circles 79 

35.  Calorimotor 80 

36.  Voltaic  pile 61 

37.  Deflaf rator  . . . 81 

38.  App.  for  decomposition  of  water    86 

39.  Transfer  of  chemical  substances    87 

40.  App.  for  change  of  colors 87 

41.  Galvanometer 99 

42.  Revolving  rectangle 93 

43.  Helix  and  rtand 95 

44.  Magnet  with  three  poles 95 

45.  Electro  magmt 95 

46.  Magic  circle 96 

47.  Vibrating  magic  circle 96 

48.  49.  Separable  helices 97,  98 

50.  Magneto-electric  machine 99 

51.  Theory  of  electro-magnetism  ...  101 

52.  Electrotype 104 

53.  Dropping  tube 119 

54.  App.  for  change  of  form 113 

55.  Ills,  of  atomic  theory 118 

56.  Specific  gravity 121 

57.  Aerometer 122 

58.  Pneumatic  cistern 129 


76. 
77. 


79. 


59.  Retorts 130 

GO.  Lead  tubes  for  connection 131 

61,  62,63.  Apparatus  for  oxygen..   J3_> 

64.  Apparatus  for  collection  of  gasea 

heavier  than  the  air l:W 

65.  App.  for  dacoMDOsJUonot  w;ii tr  ! '>'• 

66.  Gas  bag  and  bubble  pipe 

67.  Method  of  filling  gas  bags. . . 

68.  Balloons, 1  :•.» 

69.  Apfi.  for  musica  i  . .   1 1'j 

7".    If \droi;eii  pistol 149 

71.  Eudiiimrii  r 

.pmill.l     bli.WpilM) I.Xi 

73.  \Voulfe*s  Hjipnratus 

74.  App.  for  obtaining  nitrogen. . 

75.  "    for  analyzing  tli< 

for  obtaining  niti 
showing  the  properties  of 

nitric  an.l I-.H 

for  collecting  faMs  light. T 

than  the  air 17<> 

for  carbonic  acid IT* 

80.  Effect  of  gauze  wire  upon  flame  187 

81.  Safety  lamp 

82.  Platinum  wire  for  wicks 1  - v 

83.  Cry»talhr.ation  of  sulphur. . 

84.  Crucibles l'J2 

85.  Production  of  sulphur  in  volca- 

noes   r.iy 

86.  App.  for  combustion  of  pin .- , 

rus  in  oxygen 

87.  App.  forphcMphureted  hydr. 

88.  Evaporating  di»hes 908 

89.  Hexahedron 984 

90.  Right  square  prism 984 

91.  Right  rectangular  prism 

99.  Right   rh..ml...i.l:il  pn-m.... 

99.  Regular  hexagonal  prism 

94.  Rhomhohedron 985 

95.  Oblique  rhombic  prism 

96.  "        rhomboidal  prism 285 

97.  Regular  octohedron 285 

98.  Square  "  285 

99.  Rectangular  "          286 

100.  Rhombic        «          286 

101.  Dodecahedron 286 

102.  App.  analysis  of  gases 356 

103.  App.  analysis  of  minerals 3.V 

104.  App.  to  dt-tert   hydrwulphuric 

acid 

105.  Test  tubes 361 

106.  Mode  of  folding  filters 3>o 

1U7    Filters 365 

108.  App.  fur  filtration 363 

109.  Supports 363 


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